Polyendocrine metabolic ovarian syndrome (PMOS), previously called polycystic ovary syndrome (PCOS), is a common hormonal disorder in females. The condition has wide-ranging effects on the body, affecting metabolism, hair, skin and mental health, and sometimes making it hard to get pregnant, according to the Mayo Clinic.

PMOS affects over 170 million people of reproductive age worldwide, including up to 12% of U.S. women of reproductive age.

PMOS is characterized by high levels of androgens, the group of sex hormones that includes testosterone. It's often associated with resistance to insulin, a hormone that regulates blood sugar. The condition can come with a range of symptoms, including irregular periods, excessive weight gain and hair growth, and acne.

Many individuals with PMOS also have underdeveloped eggs, or "arrested follicles," lining the outer edges of their ovaries, which doctors previously labeled as cysts. However, calling these "cysts" was misleading, as people often thought they were the same as pathological noncancerous ovarian cysts, which can rupture, cause pain or bleed, and sometimes require surgery to treat.

The incorrect focus on so-called polycystic ovaries, which are neither necessary nor sufficient for a diagnosis, was part of the reason PCOS was officially renamed on May 12, 2026.

What causes PMOS?

Scientists don't know the root cause of PMOS, and there is probably more than one, Dr. Marie Menke, a reproductive endocrinologist at University of Michigan Health, told Live Science.

One possible cause is that the ovaries make excess levels of certain sex hormones, including testosterone and anti-Müllerian hormone, Live Science previously reported. This, in turn, may drive many of the other symptoms, so whatever is driving the excessive hormone production may be the key. Why some ovaries produce excess sex hormones, however, is unclear. Efforts to build better laboratory models of the ovaries could reveal the answers to some of these questions.

Obesity and insulin resistance ‪—‬ the body's inability to use insulin effectively — also may play a role in triggering PMOS, although whether these conditions are a cause or consequence of PMOS has been a matter of debate. Other studies have proposed that children who are exposed to high levels of androgens in the womb may go on to have the syndrome.

Genes play a role, too: PMOS tends to run in families, and a person whose family members have PMOS is more likely to develop it. People with a family history of type 2 diabetes are also more likely to develop PMOS, according to the World Health Organization.

PMOS and pregnancy

PMOS symptoms often start in early puberty and some persist through and after menopause. Many people find out they have the condition in their 20s and 30s, if they have trouble becoming pregnant. PMOS can make it difficult to become pregnant without fertility treatment because androgens prevent immature follicles from developing into mature eggs that can be released and develop into an embryo, according to the U.S. Office on Women's Health (OASH).

People who are hoping to get pregnant have a number of treatment options, including fertility medications, such as clomiphene (also known by the brand names Clomid and Serophene); or gonadotropins, such as follicle-stimulating hormone or luteinizing hormone, according to the OASH. Metformin, a type 2 diabetes drug, can also be used to promote ovulation.

PMOS symptoms

According to the OASH, PMOS may include these signs and symptoms:

• Infertility: People with PMOS do not ovulate regularly, so they have fewer chances per year to become pregnant
• Infrequent, irregular or absent menstrual periods
• Hirsutism, or increased hair growth on the face, chest, stomach, thumbs or toes, likely caused by excess androgens
• Ovaries that are enlarged or have many arrested follicles
• Acne or oily skin, also likely caused by excess androgens
• Weight gain or obesity
• Male-pattern baldness or thinning hair, another symptom of excess androgens
• Acanthosis nigricans: Thick, dark patches of skin on the neck, arms, breasts or thighs
• Skin tags, which are excess flaps of skin in the armpits or neck area

Diagnosis and tests for PMOS

Diagnosing PMOS can be challenging because symptoms vary a lot, Menke said. And many of them are nonspecific, meaning they're not uniquely tied to PMOS.

To be diagnosed with PMOS, a patient must experience at least two of the three main symptoms described below, Menke said:

1. Irregular menstrual cycles: Irregular, infrequent or no periods are caused by a lack of ovulation. For example, someone may have fewer than nine periods a year or have unpredictable periods.
2. Higher-than-normal levels of androgens.
3. Polycystic ovaries, identified by ultrasound. However, some patients with PMOS have normal-appearing ovaries, and other women with cysts (fluid-filled sacs) on their ovaries may not have PMOS.

Complications of PMOS

PMOS has been linked with a number of other health conditions, including:

• Metabolic syndrome: A group of risk factors for heart disease, stroke and diabetes that is twice as common in people with PMOS than the general population, according to the American Academy of Family Physicians
• Type 2 diabetes: More than half of people with PCOS develop diabetes by age 40, according to the Centers for Disease Control and Prevention
• Cholesterol abnormalities, such as high LDL ("bad") cholesterol and low HDL ("good") cholesterol, which can increase the risk for heart disease
• High blood pressure, which can affect the heart, brain and kidneys
• Sleep apnea, which can cause pauses in breathing during sleep
• Anxiety or depression
• Diabetes or high blood pressure during pregnancy

Treatment and medications for PMOS

It is difficult to treat all of the symptoms of PMOS at once, Menke said, so she typically asks her patients what their primary concern is and then focuses treatment on managing those symptoms first. For example, if someone's main concern is excess hair growth, Menke said she would typically prescribe birth control pills, which can help reduce levels of androgens.

There are treatment options to help manage the symptoms of PMOS, Menke said. According to the Mayo Clinic, treatment options may include the following:

• Birth control pills, which contain either a combination of estrogen and progestin or progestin only, can regulate menstrual cycles, reduce androgen production and help clear acne.
• Progestin hormone replacement therapy can also regulate menstrual periods. (It is not a contraceptive.)
• Fertility medications can stimulate ovulation in PMOS patients who wish to become pregnant.
• Weight-management drugs, such as GPL-1 agonists, which include medicines like Wegovy
• Anti-androgens, such as spironolactone or flutamide
• Diabetes medications, such as metformin, make the body more sensitive to insulin.
• Acne treatments and hair removal therapies, such as laser hair removal or electrolysis

This article is for informational purposes only and is not meant to offer medical advice.

Last week, PCOS got a major rebrand.

Polycystic ovary syndrome (PCOS) will now be known as polyendocrine metabolic ovarian syndrome (PMOS). The main critique of the old name was that it inaccurately described the condition, which affects about 1 in 8 women worldwide. It implied that ovaries covered in many pathological cysts are a central feature of the syndrome, and that is not the case.

Studies have found that people with PMOS aren't more likely to have pathological ovarian cysts than people without the disorder. Instead, they often have underdeveloped eggs, called "arrested follicles," that accumulate in the ovaries due to the hormonal disruptions associated with the condition. The new name, experts say, better reflects the nature of the syndrome by focusing on these hormonal disruptions that then impact metabolic processes across the body — driving insulin resistance and weight gain, for instance — in addition to affecting the reproductive system, skin, and mental health.

What do you think of the new name? Tell us in the poll below, and let us know your thoughts in the comments. If you personally have PMOS, we'd love to hear your take, in particular!

(Fun fact: PMOS has actually undergone several previous name changes. Its original name was Stein-Leventhal syndrome, after the doctors who first described its features.)

This article is for informational purposes only and is not meant to offer medical advice.

A hormonal disorder that affects 1 in 8 women just got a new name.

Polycystic ovary syndrome (PCOS) will now be called polyendocrine metabolic ovarian syndrome (PMOS). Experts say that the new name better reflects the nature of the disease.

"It was very clear that the name was inaccurate," said Dr. Helena Teede, an endocrinologist and professor of women's health at Monash University in Australia. Teede, who is also the director of the Monash Centre for Health Research & Implementation, chaired the steering group that led the name-change effort.

The decision to change the name was not made lightly. The process involved surveying thousands of people with the syndrome around the world, as well as thousands of healthcare professionals. The funding and oversight of the effort involved 56 academic, clinical and patient organizations. There's a plan to raise awareness of the new name and adopt it in practice over the next three years.

"It was a really robust process, and the community was involved at all stages," Teede told Live Science. "We hope that people will understand and respect the process — understand that it wasn't made behind closed doors with a few small expert groups, which is what normally happens."

What's in a name?

The idea to pick a new name for PCOS isn't new, with some calls for action dating to the 1990s and early 2000s. In 2012, the U.S. National Institutes of Health recommended a name change after experts concluded the name PCOS was a confusing "distraction" for both patients and providers.

"The name focuses on a criterion — polycystic ovarian morphology — which is neither necessary nor sufficient to diagnose the syndrome," NIH experts wrote in the report.

The old name implied that people with PMOS have many abnormal cysts on their ovaries, Teede explained. When the condition was first described in the 1930s, doctors physically examined patients' ovaries during operations and noticed "they looked lumpy and bumpy, like they had cysts on them," she said. "But a true abnormal cyst has a particular type of lining and behaves in a certain way."

Known as "pathological noncancerous ovarian cysts," those types of cysts can grow larger, rupture, bleed and cause pain, and they can require surgery to treat. Teede and other researchers have found that PMOS patients aren't more likely to have these pathological cysts than people without the condition. Rather, they often have a large number of "arrested follicles," meaning eggs that have failed to fully mature within the ovaries due to the syndrome's hormonal effects.

In short, the term "polycystic" is incorrect, because arrested follicles are not cysts. What's more, the focus on ovaries ignores the disruptions in multiple hormones that drive downstream issues with metabolism, weight, reproduction, the skin and mental health.

Up to 70% of people with PMOS are undiagnosed, estimates suggest, and part of that diagnostic gap may stem from misconceptions about what the condition actually is. Over the years, surveys have repeatedly suggested that both doctors and patients find the name PCOS confusing and often think abnormal ovarian cysts are a key feature of the condition. In a recent survey, nearly 86% of patients and 76% of health professionals who responded agreed that the name should change.

Because the syndrome has largely been viewed as gynecological, research, funding and medical education has often focused on the reproductive aspects of PMOS. This has left knowledge gaps among doctors in other specialties, despite the condition impacting many bodily systems. The new name could also help to turn that tide, stakeholders think.

"We needed to move away from the inaccurate towards the accurate," Teede said of the new name.

A new name, at last

After the NIH issued its 2012 recommendation, a series of renaming efforts followed, but they each failed to gain traction. Experts recognized that a successful renaming would require international leadership, a democratic process to reach consensus, the inclusion of patient advocacy groups and a clear plan to roll out the new terminology.

In addition to asking whether the syndrome should be renamed, leaders of the effort asked whether the acronym should remain "PCOS," for ease of adoption, or if it was more critical for the name to accurately reflect the disease's features. The latter turned out to be more important to respondents, the organizers reported Tuesday (May 12) in The Lancet. The new name will also be announced in person on Tuesday at the European Society of Endocrinology Conference in Prague.

"We got a very strong vote for the first two terms, which is the 'polyendocrine' and the 'metabolic,'" Teede said. Weighing the word "ovarian" proved tricker, she said, but it was ultimately chosen because other terms, such as "reproductive," were seen as more stigmatizing.

"In many cultures, the worth or value of a woman is linked to her fertility," Teede said. "So, implying that women have a condition that might impact that is — it can be very harmful."

She added that, when diagnosed and treated appropriately, people with PMOS can often bear children and achieve the family sizes they want; it's when they go undiagnosed and untreated that fertility issues can get in the way, she said.

Some experts have suggested that, with this name change, there may be an opportunity to research a possible "male version" of PMOS. Some males have low levels of androgens that cause sparse hair growth and early balding, as well as some of the same issues seen in PMOS, such as insulin resistance, obesity and mental health problems.

For her part, though, Teede doesn't think there's enough evidence to call this phenomenon in males a form of PMOS, even though it shares some similar hormonal and metabolic features. It's "way too premature, based on the science," she said. "It's a different condition in that it doesn't have the same reproductive implications as it does in females."

As follow-up work, Teede and colleagues will work to tweak some of the language used in the diagnosis of PMOS. When examining ovaries on ultrasound, doctors look for what they call "polycystic ovarian morphology," but really, they're looking for signs of arrested follicles. So to align with the syndrome's new name, that terminology will need a change, too.

For those looking for accurate information about PMOS, Teede recommended the app AskPCOS, which will soon be renamed AskPMOS.

This article is for informational purposes only and is not meant to offer medical advice.

As placental mammals, humans give birth to live young. Pregnancy begins on the first day of the last menstrual period, roughly two weeks before conception.

A human pregnancy consists of three trimesters and generally lasts around nine months. But how much do you know about how babies develop? For example, did you know some cell types appear only during pregnancy, or that hair usually grows thicker and lusher during pregnancy due to hormones, but that this extra hair falls out months later after giving birth?

Think you can conceive of all things related to pregnancies? Take this quiz to find out if you can deliver! Remember to log in to put your name on the leaderboard; hints are available if you click the yellow button. Good luck!

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Doctors had little hope for a fetus with a fatal lung condition, but at his parents' urging, they performed an unprecedentedly early operation during which they partially removed him from the womb.

The procedure saved the child's life — baby Cassian was born in August 2025 and is still doing well. The doctors hope the same approach will save others in the future.

The diagnosis came during a second-trimester ultrasound at Orlando Health Winnie Palmer Hospital for Women & Babies in Florida. The scan revealed overinflated lungs and a compressed heart — signs of a dangerous condition called congenital high airway obstruction syndrome (CHAOS).

Normally, developing lungs make secretions that travel up the windpipe and are swallowed. In CHAOS, a blockage in the windpipe stops the secretions from traveling up and out of the lungs, causing the organs to swell and compress the heart.

CHAOS affects just 1 in 50,000 pregnancies, and without treatment, the condition is fatal.

"Due to the relative infrequency of the condition, there is not a single, well-established standard of care for treatment," Dr. Cole Greves, one of Cassian's surgeons, told Live Science in an email. "Many cases must be individualized to the unique circumstances of the maternal and fetal patients."

A risky strategy

A scope revealed that the blockage in Cassian's widepipe was a 0.2-inch-thick (5 millimeters) membrane, which was too large to puncture using a minimally invasive laser probe.

Doctors have a method for safely delivering babies with these types of airway obstructions. Ideally, they wait until weeks 37 to 39 of pregnancy before using a variant of a cesarean section that involves delivering the head, neck and shoulders of the fetus first while the lower body remains in the womb. At this point, the baby is effectively half born.

Doctors then insert a catheter to bypass the blockage, drain the fluid and allow the baby to breathe, before clamping the umbilical cord and delivering the baby completely. This procedure, called the ex-utero intrapartum treatment (ExIT), is routinely performed on patients with CHAOS.

However, 1 in 4 fetuses with CHAOS die of heart failure before reaching those final weeks of pregnancy, said Dr. Emanuel Vlastos, another one of Cassian's fetal surgeons. This scenario seemed probable for Cassian, whose heart couldn't grow properly under the pressure of his distended lungs.

Cassian's parents urged doctors to try anything they could, leading the medical team to propose a potentially risky operation. At just 25 weeks, they would perform the ExIT, drain Cassian's lungs of fluid before his heart condition worsened, and place him back in the womb to continue developing.

"When you hear the parents say something to the effect of, 'Well, we know this may not work out, but if you can learn something and help another child, it's probably going to be worthwhile' — that's a pretty magnanimous thing for a parent to say, knowing their baby may die," Vlastos said.

With permission from an ethics committee, the surgeons operated on Cassian and his mother Keishera at 25 weeks of pregnancy. This involved conducting a C-section to expose Cassian's head and neck and then inserting a catheter into his windpipe to drain his lung secretions. Then, they returned his upper body into the womb and closed it. The catheter remained, held firmly in place by an inflated balloon in his windpipe, for the remainder of the pregnancy.

Given that the ExIT is typically performed at the time of child birth, this may be the first time doctors inserted a windpipe catheter into a fetus this early in gestation and returned him to the uterus, Greves said.

Balancing two lives

Operating on a fetus requires factoring in the mother's health, too.

"It is a tightrope walk, sometimes for several hours, while two lives hang in the balance," Greves said.

In this case, the team used general anesthesia to sedate mother and child, but doctors aren't sure what effects general anesthesia has on the developing nervous system of a 25-week fetus, Vlastos noted. Some studies suggest anesthesia can disrupt the formation of links between nerve cells and lead to cognitive issues, for example.

But it was imperative to sedate the fetus so he wouldn't attempt to breathe once exposed to air. "There's a whole lot of circulatory changes that potentially could happen if the baby tried to breathe," Vlastos said. And those changes could make it impossible to carry out the rest of the pregnancy.

Fetuses receive oxygen via the placenta rather than by breathing themselves; in the womb, a blood vessel called the ductus arteriosus forces oxygenated blood to bypass the immature lungs and directs it to the rest of the fetal body. "Once kids start to breathe outside of the womb, that vessel begins to slowly close" so that blood can travel to the lungs to pick up oxygen, Vlastos said. The doctors would not have been able to return Cassian to the womb if he had begun breathing.

For Cassian's mother Keishera, general anesthesia ensured that her uterine muscles relaxed during the procedure. Otherwise, "the baby's going to erupt" and be delivered early, Vlastos said, as the uterus is prone to contract when incised. What's more, a surgically opened uterus can expel a lot of blood if it starts contracting, leading to a potentially dangerous hemorrhage for the mother.

Another concern with operating on a preterm fetus is disrupting the delicate process of development. For example, if the balloon that held the catheter in place were underinflated, the catheter could have slid down and put pressure on the windpipe, preventing it from developing, Vlastos said. And if it were overinflated, the balloon could compress the blood vessels draining the head, causing circulatory issues, he added.

Inflating a balloon in the widepipe could pose a number of concerns, Dr. Diana Farmer, a fetal surgeon at the University of California, Davis Health who was not involved in this case, told Live Science in an email.

But "I like to say 'there's a lot we can do for a live patient,'" she said. "And the tracheal issues can be dealt with after birth."

The outcome

At week 31 of pregnancy, six weeks out from the daring surgery, Keishera's uterus started contracting and the time came to deliver baby Cassian. Scarring from the earlier surgery may have made her more likely to go into labor early.

A team of 30 people assembled at 3 a.m. to perform an ExIT, as had been planned, Vlastos said.

The team exposed Cassian's head and neck and swapped the fluid-draining catheter in the windpipe for an intubation tube to help the newborn breathe. He was born relatively healthy, although he needed to remain in the hospital for a few months due to being born prematurely.

Today, Cassian remains on a ventilator but is being weaned off respiratory support. When he's older, he'll require surgery to clear the obstruction in his windpipe and allow his breathing tube to be removed for good.

Cassian's story shows that this early intervention can work, fostering hope for other CHAOS cases.

"This work would best be carried out in the context of a clinical trial with rigorous data collected on the development impacts of the lung and tracheal growth," Farmer said. "But these are difficult to accomplish in rare diseases."

Vlastos said fetal surgeons, globally, should come together to discuss whether they have performed similar operations and to think of new strategies to improve the surgery. For instance, they could find smaller catheters that are more appropriate for a fetus or develop less invasive approaches to drain the lungs.

Cassian's surgery may sow the seeds for doctors to perform similar operations in the future, but it would never have happened if it weren't for the trust of his parents.

"They never stopped asking the very important question, 'What else could we try?'" Greves said. "I do believe, in the end, this made all the difference."

This article is for informational purposes only and is not meant to offer medical advice.

A blood-filtering technique could be a promising treatment for preeclampsia, a potentially deadly disorder of pregnancy that involves high blood pressure.

The new therapy is safe for both the pregnant person and the fetus, according to a new pilot study published Monday (April 27) in the journal Nature Medicine. Future trials will examine how well the treatment works, but early data hints that it can reduce circulating levels of a placental protein linked to the disease.

Although low-dose aspirin has been shown to reduce the risk of preeclampsia in high-risk patients, no intervention has been successful at treating the condition once it has been diagnosed.

Now, "we're finally on the verge of developing a targeted treatment for this condition," study co-author Dr. Ravi Thadhani, a nephrologist and chief medical officer at Cedars-Sinai Medical Center in Los Angeles, told Live Science.

A new avenue for treatment?

Currently, the only way to address preeclampsia is for the pregnant patient to give birth, although the condition can sometimes persist postpartum or even develop after birth.

Ideally, preeclampsia is managed and monitored until the baby reaches full term, at 37 weeks. But that's not always possible, meaning babies are often delivered prematurely. Preterm delivery can lead to health issues such as breathing problems and developmental disabilities, especially if the baby is born before 32 weeks gestation.

For the pregnant person, preeclampsia can cause dangerous damage to the liver, kidneys and heart, among other issues. And if not treated, it can lead to eclampsia, which involves seizures and can result in coma or death.

Thadhani hopes the blood-filtering treatment can "prevent this disease from getting worse and forcing the hand of the obstetrician to deliver" prematurely.

The new treatment relies on a technique called apheresis, in which blood is drawn and then returned after select components are removed. In this case, a protein called soluble fms-like tyrosine kinase-1 (sFlt-1) gets filtered from the bloodstream. sFlt-1 increases in the bloodstream during healthy pregnancies to regulate blood vessel formation around the placenta, but its levels often rise earlier and by excessive amounts in preeclampsia, causing vascular damage that may contribute to the condition.

Thadhani and colleagues previously demonstrated that the ratio of sFlt-1 to placental growth factor, another circulating protein, could predict the risk of preeclampsia, with a ratio of 40 or above tied to an especially severe form of the disease. Based on this finding, and additional studies from their lab and other groups, they reasoned that sFlt-1 might be good to target with a treatment.

They first administered the therapy to three pregnant baboons, observing that each treatment session decreased circulating sFlt-1 by about 50%. They then confirmed the treatment's safety in healthy human volunteers who were not pregnant before moving to test it with pregnant patients.

They recruited 16 patients with preterm preeclampsia, which is diagnosed before 34 weeks of pregnancy; the participants were a median of 30 weeks pregnant upon hospital admission. Seven participants received a single session of the therapy, which confirmed that the strategy could safely reduce sFlt-1 in people. The remaining nine patients then underwent between one and three treatment sessions. In this latter group, each treatment session brought sFlt-1 levels down by nearly 17%, although these levels rebounded in some patients.

The main purpose of this small study was to confirm the treatment's safety, and the participants weren't compared directly with untreated patients. Still, the participants who were treated carried their pregnancies for a median of 10 days after their hospital admission, while a group of untreated patients who weren't enrolled in the study carried for only four days post-admission.

These results suggest that the treatment can prolong pregnancy in preterm preeclampsia, though a proper clinical trial is needed to know for sure.

More to learn

While Thadhani's team is targeting sFlt-1 levels, some scientists disagree about how the protein contributes to preeclampsia.

"The camps are still split on whether it has a role in preeclampsia development or it's a consequence of something else happening in the body," said Dr. Lana McClements, leader of the Cardio-Obstetrics Research Group at the University of Technology Sydney, who was not involved with the study.

Not all cases of preeclampsia are alike, McClements said, and multiple factors other than sFlt-1 may drive the disease. That said, Thadhani and his collaborators focused on testing the treatment in participants with early-onset preeclampsia, which is associated with high sFlt-1 levels. In that way, they may have identified a suitable patient population for their approach, she said.

McClements called the pilot study's results "promising," but she noted that sFlt-1 levels dropped by less than 17% in the human patients following each treatment, compared with around 50% in the baboon experiment. And in people, the levels sometimes rebounded and then plateaued.

Based on this pilot study, Thadhani plans to test the treatment with a gold-standard clinical trial and at earlier time points in pregnancy.

"The women that we treated in this paper were quite sick," he said. "They were literally on the verge of delivery. The next step here is to start earlier so that we can deliver more treatments and keep the disease more quiet."

This article is for informational purposes only and is not meant to offer medical advice.

An extreme form of nausea and vomiting during pregnancy is linked to 10 genes, one of which is likely the main culprit behind the condition, according to the largest genetic study of its kind to date.

Most people experience some degree of nausea and vomiting during early pregnancy, but up to 10.8% have symptoms so severe that they stop being able to eat and drink and may even require hospitalization. This condition, called hyperemesis gravidarum (HG), can last throughout a person's entire pregnancy, but it currently lacks any Food and Drug Administration-approved treatments.

Now, a new study, published Tuesday (April 14) in the journal Nature Genetics, provides evidence that the gene for the hormone growth differentiation factor 15 (GDF15) is the leading cause of HG, which has been suggested in other studies.

The research also identified six additional genes with ties to the condition, including one that may control the production of glucagon-like peptide-1 (GPL-1), a hormone involved in regulating insulin and appetite. The gene is also the greatest known genetic risk factor for type 2 diabetes.

These findings could spur the development of new treatment options and targets for HG.

"It's going to be helpful as far as exploring new avenues for therapies and exploring ways to better predict, diagnose, treat and potentially prevent HG in the future," study first author Marlena Fejzo, an expert in HG at the Keck School of Medicine of the University of Southern California, told Live Science. Fejzo consults for a pharmaceutical company trialing a GDF15 drug.

Finding the cause of HG

The pregnancy hormone human chorionic gonadotropin (hCG) — the first hormone made by the placenta after conception — was long thought to underpin HG because its levels surge in early pregnancy. Estrogen was also suggested as a possible cause, as its levels also rise dramatically.

But recent research by Fejzo and her colleagues has zeroed in on GDF15 as a likely cause of HG. They've pinpointed specific mutations in the GDF15 gene that significantly boost the risk of the condition, with one rare mutation increasing the risk tenfold.

But because the researchers identified this genetic risk factor primarily using data from people of European ancestry, Fejzo said she wanted to see if the finding generalized to more diverse populations.

So, in the new study, the team combined data from nine independent studies of HG from across the U.S. and Europe. They compared the whole genomes and autosomes — the chromosomes excluding the X and Y sex chromosomes — of nearly 11,000 people with diagnosed HG and over 420,000 people with a history of pregnancy but no HG. Most data still came from individuals of European descent, but the datasets also included roughly 13,000 people of Asian ancestry, over 1,200 people of African ancestry, and 75 people of Latino ancestry.

The team found 10 genes associated with a heightened risk of HG, with the gene for GDF15 as the top signal across all populations, Fejzo said.

"These are associations, so we can't necessarily say that they're causative," she said. However, this study provides indirect evidence for a causal link between HG and GDF15, given the strength and generalizability of the signal, Fejzo said.

Ultimately this large study's findings, combined with the previous work by Fejzo's team and other groups, establishes a causal link between GDF15 and the condition, she said.

In a first, the researchers also identified an association with TCF7L2, the leading genetic risk factor for type 2 and gestational diabetes, which is new-onset high blood sugar in pregnancy. Previous research found that this gene may regulate GPL-1, the same hormone mimicked by drugs like Ozempic and Wegovy.

Fejzo said this discovery "seems like a fascinating new target to explore" to develop new drugs for HG.

Other genes pinpointed in the study are linked to learning and memory, while others are tied to wasting syndrome and appetite. No genetic links to hCG or estrogen were identified in the work, the authors wrote in the paper.

This "incredibly well-done" research "cements" the GDF15 pathway as the primary driver of HG across a wide and diverse population, said Dr. Andrew Housholder, an emergency physician who specializes in HG and consults for a pharmaceutical company trialing a GDF15 drug.

"It should finally end the discussion of HG as a sensitivity to hCG and estrogen," Housholder, who was not involved in the research, told Live Science in an email.

Each of the 10 genes identified "deserves deep study," he added. The fact that they span many major biological pathways, touching on everything from insulin signaling to learning, "really illustrates how complex a disease process HG is."

The exact reason learning and memory genes are linked is unclear, but one theory suggests they may play a part in wiring the extreme food aversion responses seen in people with HG, Fejzo said.

Fejzo and her team aim to launch a clinical trial this summer. It will involve giving metformin, a diabetes medication that increases GDF15, to patients with a history of HG. The patients being enrolled are planning to have more children in the near future, so the trial will test whether metformin desensitizes them to GDF15 ahead of conception. The hope would be to reduce their nausea and vomiting once they are pregnant.

While treatments are being explored, Fejzo said people can find guidance and support on the website of the Hyperemesis Education and Research (HER) Foundation, which supports research, advocacy and education on HG. Fejzo is a voluntary board member and the research director of the HER Foundation.

This article is for informational purposes only and is not meant to offer medical advice.

A new study suggests that human sperm quality follows a seasonal pattern, peaking in the summer and dipping in the winter.

The research, published Feb. 21 in the journal Reproductive Biology and Endocrinology, analyzed semen samples from more than 15,000 sperm donors in Denmark and the U.S., specifically the state of Florida. Across both populations, the scientists found a consistent pattern: the highest levels of progressively motile sperm — sperm that can swim efficiently in a straight line — appeared in June and July, while the lowest levels occurred in December and January.

Seeing this pattern, "we wondered if men might have more chance of being accepted as a [sperm] donor if they apply in the summer," study co-author Allan Pacey, a professor of andrology at the University of Manchester, told Live Science in an email. "By extension, it may also mean that couples in Denmark and Florida who want to try for a baby might do better in the summer. But that is just a theory."

​​Dr. Sherman Silber, a urologist and director of The Silber Infertility Center of St. Louis, who was not involved in the study, doesn't think the seasonal variation in sperm motility is likely to affect real-world fertility. The differences reported in this study are "very, very tiny" and "make no difference whatsoever biologically," he told Live Science in an email.

Lifestyle influence or evolutionary relic?

To explore sperm quality over time, the researchers analyzed semen samples from 15,581 men ages 18 to 45 who applied to be sperm donors between 2018 and 2024. Samples were collected in four Danish cities — Aarhus, Aalborg, Odense and Copenhagen — as well as in Orlando, Florida.

The team used computer-assisted sperm analysis to measure semen volume, sperm concentration and the number of progressively motile sperm in each sample. (Progressively motile sperm swim in straight lines or large circles, while non-progressively motile sperm move in tight circles but do not travel forward.)

Because sperm take about 74 days to develop in the body, the researchers also examined whether temperatures in the weeks leading up to ejaculation might influence sperm quality. But they found little evidence that either temperatures at the time of ejaculation or those from two months prior had any measurable link to sperm quality.

That said, temperature may indirectly influence sperm quality by influencing lifestyle factors known to affect sperm quality, the researchers hypothesized.

"The fact that the seasonality still existed when we accounted for ambient temperature made us think that other lifestyle changes might be important," Pacey said. "This could include diet, exercise, exposure to sunlight. But we did not measure these things so we can only speculate."

Silber thinks the seasonal pattern may be an evolutionary vestige. In many animals living in temperate climates, reproduction is timed so that offspring are born in spring, when conditions are more favorable and resources more abundant. If sperm quality peaks in summer, that timing could increase the likelihood of spring births. In humans, however, this seasonal effect is likely muted since humans have adapted to survive well in the winter, Silber proposed.

Different studies, different trends

Previous studies have also reported seasonal changes in sperm quality, but the documented patterns were inconsistent. Some research, including a study from Italy, also found peak sperm motility during the summer, in line with the new findings.

But other studies have reported the opposite trend. For instance, a large analysis of more than 21,000 semen samples from southern China found that sperm motility peaked in late winter and declined through the summer months. The differences between these studies hint that regional lifestyle and environmental factors, such as differences in temperature, humidity, or social behaviors, may shape how sperm quality fluctuates over time, the study authors wrote in the new paper.

In addition to seasonal variation, the new research found strong links between sperm quality and age. Sperm motility was highest among men in their 30s, and lower in men younger than 25 and older than 40.

The researchers also observed a significant dip in sperm quality in Denmark between 2019 and 2022, followed by a rebound in 2023, possibly reflecting lifestyle changes during the COVID-19 pandemic. For instance, lockdowns altered the general public's working patterns, diet, and physical activity levels, and previous studies suggest that each of these factors can influence sperm motility.

In contrast, sperm quality in Orlando increased gradually from 2018 to 2024, a trend that remains unexplained and warrants further study, the study authors noted.

This article is for informational purposes only and is not meant to offer medical advice.

Scientists have unveiled a detailed "atlas" of the placenta and uterus, showing how these unique tissues grow and evolve throughout pregnancy to accommodate a developing fetus.

In charting this new map, the scientists revealed a subtype of cell that had never been described before and appears to be unique to pregnancy.

These cells are not present in the uterus outside pregnancy, and they suddenly rise in number at the start of gestation as the uterine lining morphs to cradle and support the embryo, explained study first author Cheng Wang, a specialist in regeneration medicine specialist at the University of California, San Francisco (UCSF).

"That was an exciting moment during the study," study senior author Jingjing Li, an associate professor of neurology at UCSF who studies human genomics, said of the cells' discovery. "We asked around — no one knows what they are."

These newly described cells seem to be involved in linking the placenta to the maternal blood supply, and they carry receptors that respond to cannabinoids. Cannabinoids include body-made chemicals, as well as the cannabis compounds THC and CBD. Therefore, the researchers suspect these cells may help to explain why cannabis use in pregnancy is tied to health consequences such as decreased blood flow to the placenta; poor oxygen delivery to the fetus; and a heightened risk of preterm birth, low birth weight and NICU admission.

It's unlikely that these cells' sensitivity to cannabinoids fully explains the risks posed by cannabis use in pregnancy, Li told Live Science; other potential culprits have been described in the medical literature. Nonetheless, these newfound cells are a factor that warrant further study, he said.

A crucial "speed bump"

Prior to the new study, published April 8 in the journal Nature, other research groups had mapped the placenta and uterus using similar techniques. However, those previous studies covered only select chapters of pregnancy.

"The biggest difference is we are looking at the whole time course" from early pregnancy to birth, Li said. The new atlas incorporates data from tissues that were collected between weeks 5 and 39 of pregnancy and then stored in tissue banks at UCSF and Stanford University.

Li's lab analyzes tissues in great detail, at the resolution of single cells, with placental development being one of the team's major research focuses. Their new atlas incorporates snapshots of which genes were active and which proteins were present in the analyzed cells at a given stage of pregnancy. It also looks at "chromatin accessibility," which reflects how DNA molecules are packaged within the cell and which genes can be activated at a given moment.

In total, the team analyzed about 1.2 million placental and uterine cells, including 200,000 isolated cells and 1 million cells embedded in their original locations within the tissue.

Looking at isolated cells can be helpful for pinpointing their identities, but the approach lacks the context of "where these cells are located within the tissue, which cells they are near, and how they interact with one another," Roser Vento-Tormo, a group leader in cellular genomics at the Wellcome Sanger Institute, and her postdoc Ana Paredes told Live Science via email. In the uterus and placenta, cells are arranged in distinct regions with different functions.

By combining these two techniques, "this study provides a clear example of how cell location and state can yield important biological insights into how a healthy pregnancy is orchestrated at the cellular and molecular level," said Vento-Tormo and Paredes, who were not involved in the research.

The work revealed interesting links between a given cell's gene activity and its behavior.

For instance, early in pregnancy, certain fetal cells invade the uterus and its major arteries, helping to establish blood flow to the placenta. Using machine learning, the researchers predicted how deeply a given cell would invade the uterus based on its gene activity.

When this invasion goes awry — for example, if cells do not penetrate deeply enough or they penetrate too deeply — it can contribute to complications like preeclampsia or placenta accreta, Vento-Tormo and Paredes said. "For a healthy pregnancy, this invasion needs to be very precisely controlled," they noted.

It turns out that the new cell type identified by the researchers helps to regulate the invasion. By sending out specific signals, the cell type acts as a "speed bump" to prevent the process from proceeding too quickly, Li said.

"It's at the frontline of the maternal-fetal interface," Weng told Live Science. Various proteins carried by these cells support this idea that they're regulating the behavior of other cells at this crucial interface, he said.

Future research could address whether changes in this signaling contributes to pregnancy disorders, as well as whether there may be treatment opportunities in targeting the pathway, Vento-Tormo and Paredes suggested.

With their completed map in hand, the researchers married their findings with data from huge genetics studies of preeclampsia, preterm birth and pregnancy loss. Those published studies had uncovered links between specific gene variants and the risk of these complications. The team could then pinpoint the specific cells in the placenta and uterus that actively use those genes and are therefore most vulnerable to the conditions.

"The question is, 'In which cell type will those high-risk variants take effect?'" Li said. "This will help us to know which cells are underlying those complications" and potentially develop treatments that target those cells in the future.

While the study brings together a trove of data, Li emphasized that there's more work to be done. The study focused on healthy pregnancies, so there's still a question of how pregnancies impacted by various conditions differ from this baseline. The team is now working with clinical partners to start making those comparisons. Overall, they aim to increase the total number of cells analyzed to make sure they're capturing the full diversity of cells in the pregnant uterus.

Vento-Tormo and Paredes suggested the new atlas could be combined with existing datasets, including one of their own, to help refine scientists' understanding of specific placenta cell types and their regulators. Some of the study's key findings could also be checked in laboratory models of the placenta.

"If we include more cells, more samples, a lot of new, exciting discoveries could be made," Li said. "So this is really a starting point."

Editor's note: This story was updated on April 9, 2026, to add comments from Ana Paredes and Roser Vento-Tormo.

This article is for informational purposes only and is not meant to offer medical advice.

Endometriosis is a painful, debilitating condition affecting 10% of women worldwide. It occurs when tissue similar to the lining of the uterus (known as lesions) grows elsewhere in the body — usually within the pelvis.

Treating endometriosis can be difficult. Usually, treatment involves either preventing the growth of these lesions in the first place or removing lesions surgically. But even when lesions have been surgically removed, symptoms often don't go away.

Traditionally, endometriosis has been thought of as a gynecological condition. But mounting evidence suggests this characterization downplays the disease's complexity. Endometriosis appears to affect far more than just the reproductive system. According to a growing body of research, it influences immune function throughout the whole body.

Recognizing it as a whole-body, immune-driven disease could help explain why symptoms range far beyond pelvic pain. It would also explain why treatment is so challenging and often does little to reduce symptoms.

A disease of the whole immune system

Inflammation — the body's natural response to injury or illness – is a normal part of immune response. It also plays a key role in the menstrual cycle.

But if inflammation becomes chronic or uncontrolled, it can cause problems. This is seen in autoimmune conditions such as rheumatoid arthritis, where the immune system overreacts even when there is no threat.

Chronic inflammation is also known to play a central role in endometriosis. But the effects of this uncontrolled immune response may be far more widespread than previously thought. According to recent research, the immune response appears to extend into the bloodstream and other body systems. This may explain why endometriosis causes such far-reaching, whole-body symptoms.

In people with endometriosis, immune cells appear to be less able to clear lesions. Yet, at the same time, people with endometriosis have higher levels of immune proteins such as IL-6 and IL-1β in their blood. These immune proteins, known as cytokines, are a type of messenger released by cells to promote inflammation.

Together, these dysfunctional cells make it possible for lesions to grow and persist. This immune dysregulation also has ripple effects across the body, contributing to the wide range of symptoms sufferers experience.

For instance, many people with endometriosis experience debilitating fatigue, cognitive difficulties (such as "brain fog") and widespread pain. These symptoms are rarely emphasized in clinical guidelines, yet they're often as disruptive as pelvic pain itself.

Systemic inflammation offers a compelling explanation for these symptoms. Circulating cytokines, such as those mentioned earlier, are known to influence brain function and energy regulation. Higher levels of cytokines (including IL-6) have also been linked to poorer concentration, disrupted sleep and fatigue in some autoimmune and chronic pain disorders.

These same processes may be occurring in endometriosis. This suggests that invisible symptoms could be biological consequences of ongoing inflammation — not secondary effects of pain.

A dysfunctional immune system may also help to explain why emerging research hints at an overlap between endometriosis and autoimmune diseases.

In 2025, a large scale study looked at 330,000 patients with endometriosis and 1.2 million controls (people who didn't have the condition). The study found that compared to the controls, people with endometriosis had roughly twice the odds of being diagnosed with an autoimmune condition — such as rheumatoid arthritis, lupus, multiple sclerosis or Hashimoto's disease — within two years of their endometriosis diagnosis.

This doesn't mean endometriosis is itself an autoimmune disease. But it does suggest shared mechanisms — including chronic inflammation, dysregulated immune cell activity, and problems with the immune system recognizing the body’s own tissue properly.

These overlapping features strengthen the case for understanding endometriosis as a systemic immune disorder.

Reframing endometriosis

Viewing endometriosis in this way could transform how it's diagnosed, treated and understood. It could also help us get closer to finding a solution for the condition.

Current treatments primarily target the reproductive system. But if endometriosis involves widespread immune dysfunction, then therapies that modulate immune pathways may offer more effective long-term relief.

Seeing endometriosis as a systemic condition can empower patients, as well. This reframing may help them understand that symptoms such as fatigue, joint pain, cognitive difficulties and immune sensitivity are not imagined or unrelated. Rather, they’re part of the condition’s broader biology.

Seeing it this way may support patients in advocating for themselves in healthcare settings, where systemic symptoms are often dismissed or deprioritized.

A systemic framing also opens space for patients to explore complementary management strategies aimed at reducing inflammation or improving overall wellbeing. While not curative, some people find gentle movement, stress regulation techniques and heat–cold contrast therapy helpful for managing pain or inflammatory flares.

A growing body of research shows that endometriosis is not solely a reproductive condition or a "bad period." It's a multi-system, inflammatory disorder with far-reaching health effects throughout the body.

Understanding endometriosis as a systemic immune disease is a crucial step toward better treatments, better support and, ultimately, better health outcomes.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

The patient: A 16-year-old girl in the United Kingdom

The symptoms: The teenage girl was referred to a pediatric-adolescent gynecology clinic in 1999, doctors wrote in a case report. She had pelvic pain that followed the regular pattern of a menstrual cycle, but she had not yet had her first period. She was referred for "amenorrhea," or the absence of menstruation.

What happened next: A pelvic ultrasound and MRI revealed that although the girl had a uterus, she lacked both a cervix and a vagina. The doctors later confirmed their findings with a laparoscopy, a procedure in which a tube with a camera is guided into the body through a keyhole incision. They saw no cervix or vagina, but they did see healthy ovaries and fallopian tubes with no evidence of endometriosis.

The diagnosis: The total absence of a cervix at birth, known as cervical agenesis, is one form of cervical atresia, a rare condition involving cervical malformations believed to affect 1 in 100,000 to 1 in 80,000 births.

Vaginal agenesis often accompanies cervical atresia. One small study of 18women with a missing or malformed cervix found vaginal agenesis in about 39% of patients. The rate may be much higher among women with complete cervical agenesis, the available data hint.

The treatment: The girl began taking oral contraceptives to stop her periods. Often, monthly birth control pill regimens include a week of inactive pills that contain no hormones and trigger bleeding similar to a period. In this case, though, the girl took hormonal pills continually to stop all bleeding.

The medical team then explored various surgical options for treatment, including removal of the uterus. After conversations with the girl and her family, the doctors opted to perform fertility-sparing surgery instead, conducting a vaginoplasty. During the procedure, they created a vagina with a cervical opening where it connected to the uterus.

After the surgery, the girl moved to a cyclical schedule of her contraceptive pills, meaning she started including a hormone-free week to allow for monthly bleeding. Her period began a month after the procedure.

Years later, in 2010 at age 28, she stopped taking birth control because she and her partner wanted to start trying for a child. After attempting to conceive for a year, the couple sought out fertility specialists. A hormone test indicated that her egg count was lower than average for her age. A pelvic MRI also revealed a small buildup of menstrual blood in the uterus, suggesting that scar tissue might be obstructing the upper portion of the vagina

Doctors performed a procedure to prevent future structural issues and attempted three rounds of intrauterine insemination, in which sperm from the patient's partner was delivered into her uterus via a tube called a cannula.

When this assisted reproductive method was unsuccessful, doctors pivoted to in vitro fertilization (IVF), during which eggs retrieved from her body were fertilized with the partner's sperm to form embryos that were then placed into the uterus. After three unsuccessful rounds of this approach, the couple stopped fertility treatment for financial reasons.

But in 2022, eight years after the last round of IVF, the woman became pregnant via natural conception. She delivered a healthy son via an elective cesarean section on her 40th birthday.

What makes the case unique: Natural conception is uncommon for women who undergo surgery to correct cervical and vaginal atresia.

One systematic review looked at 121 patients across 21 research studies who receive a similar surgery to the woman described in the above report. Of those, only six went on to conceive a child naturally.

The woman's pregnancy was even more notable because it occurred about a decade after she'd undergone unsuccessful fertility treatments.

In a patient perspective included in the case report, she wrote: "I am extremely grateful to [my doctor] for challenging the status quo and his experimental drive to help me have a normal sex life, menstrual cycle, become pregnant, and carry my own child."

For more intriguing medical cases, check out our Diagnostic Dilemma archives.

This article is for informational purposes only and is not meant to offer medical advice.

Catching COVID-19 during pregnancy significantly raises the risk of the blood-pressure disorder preeclampsia — but getting vaccinated protects against this serious pregnancy complication, new research finds.

Studies have consistently shown that COVID-19 can worsen pregnancy outcomes. The new findings suggest that, during the pandemic, the coronavirus infection raised the risk of preeclampsia by 45% among pregnant women who caught it, compared to those who did not. Unvaccinated women who caught COVID-19 saw their risk rise by 78%.

Vaccination, meanwhile, lowered the risk of preeclampsia. In people who completed both an initial COVID-19 vaccine regimen and got an updated booster shot, the risk fell by 33%, overall. And it fell by 58% among people with preexisting medical conditions, like diabetes, who got a booster dose.

If these findings are confirmed, they would be a "breakthrough" in understanding the potential links between preeclampsia and viruses, co-lead study author Dr. José Villar, a professor of perinatal medicine at the University of Oxford, told Live Science.

"A protective effect"

About 3% to 8% of pregnant people develop preeclampsia, typically in the second half of pregnancy or shortly after childbirth. Preeclampsia is marked by persistent high blood pressure and, often, protein in the urine, which is a sign of kidney damage. It can also cause vision problems, vomiting, severe headaches, or sudden swelling of the face, hands or feet.

Preeclampsia can cause serious complications, including damage to the liver and kidneys, strain on the heart, and disruption to the placenta's blood supply. It can sometimes progress to eclampsia, which involves brain swelling, seizures or coma. Both preeclampsia and eclampsia can be life-threatening for both the mother and the baby.

Scientists don't know exactly what causes preeclampsia. There's some research to suggest it arises from abnormal development of the placenta, but it's not completely clear whether placental dysfunction drives preeclampsia or is a consequence of it. That said, there is emerging evidence that viral infections, such as COVID-19, may play a role in some cases by triggering changes in the immune system and causing blood-vessel dysfunction, the key process behind preeclampsia symptoms.

Villar's team speculated that COVID-19 vaccines might help curb that risk by lowering the odds of COVID-19 infection and severe illness. They also theorized that vaccination may boost the immune system overall, thereby protecting against other infections and damage to the blood vessels.

For the study, which was published Feb. 18 in the journal eClinicalMedicine, the researchers analyzed data from more than 6,500 women in 18 countries who were pregnant between 2020 and 2022. One-third of the participants were diagnosed with COVID-19 during pregnancy. About 58% were unvaccinated for COVID-19 at the time their data was gathered. Among the remaining women, about 31% got a booster dose in addition to completing their original vaccination series.

Vaccination seemed to offer a "protective effect" against preeclampsia, the researchers said, and booster shots added an extra defense. Notably, women who got booster shots also had lower rates of poor pregnancy outcomes overall — measured as an index score that included events like preterm birth, admission to an intensive care unit, and more — compared with unvaccinated women.

That's in line with research published in 2024 that found women who got at least one COVID-19 shot were less likely to have preterm births, experience stillbirth, or have a baby who was small for their gestational age than unvaccinated people were.

"Vaccinations are safe and are protective for several risks," said Dr. Elena Raffetti, an assistant professor at the Karolinska Institute in Sweden and first author of the 2024 report. "There was not at all an increased risk of preeclampsia among women who were vaccinated," added Raffetti, who was not involved in the new study.

The authors of the latest study emphasized that their findings support current vaccine guidance. The American College of Obstetricians and Gynecologists recommends that pregnant people get an updated COVID-19 vaccine at the earliest opportunity — either while trying to get pregnant, during any trimester of pregnancy, or while breastfeeding or in the postpartum period.

The new analysis does have some limitations. For example, while the researchers tried to control for factors that could influence the results — such as the women's ages, smoking history or health issues linked to preeclampsia, such as previous high blood pressure and diabetes — Villar said there may be other differences between the vaccinated and unvaccinated groups that contributed to their risks.

The study authors said future research into preeclampsia's causes should focus on how the immune system responds to both infections and vaccines, and why infections like COVID-19 seem to raise the risk of the condition.

Villar noted that much is still unknown about what causes preeclampsia, meaning any new insight can help researchers understand this "major disease affecting the mother and the fetus."

This article is for informational purposes only and is not meant to offer medical advice.

Menopause is a key period in a woman's life. This transition is often accompanied by wide-ranging physical and psychological symptoms — some of which can be debilitating and affect daily life. Menopause has also been linked to cognitive problems — such as memory, attention and language deficits.

To mitigate the effects of menopause — including hot flashes, depressive symptoms and sleep problems — many women turn to hormone replacement therapy (HRT). In England, an estimated 15% of women are prescribed HRT for menopause symptoms. In Europe, this number is even higher — varying between 18% in Spain to 55% in France.

But there's limited understanding of the effects of menopause and subsequent HRT use on the brain, cognition and mental health. To address this, we analyzed data from nearly 125,000 women from the UK Biobank (a large database containing genetic and health data from about 500,000 people).

We placed participants into three groups: pre-menopausal, post-menopausal and post-menopausal with HRT. The average age of menopause was around 49 years old. Women who used HRT typically began treatment around the same age.

In short, we found that menopause was associated with poorer sleep, increased mental health problems and even changes within the brain itself.

Post-menopausal women were more likely than pre-menopausal women to report symptoms of anxiety and depression. They were also more likely to seek help from a GP or psychiatrist and to be prescribed antidepressants.

Sleep disturbances were more common after menopause, as well. Post-menopausal women reported higher rates of insomnia, shorter sleep duration and increased fatigue.

Brain imaging analyses also revealed significant reductions in grey matter volume following menopause. Grey matter is an important component of the central nervous system which is composed mainly of brain cells. These reductions were most pronounced in regions critical for learning and memory (namely the hippocampus and entorhinal cortex) and areas key in emotional regulation and attention (termed the anterior cingulate cortex).

Notably, the hippocampus and entorhinal cortex are among the earliest affected in Alzheimer's disease, the most common form of dementia.

The changes we observed in our study could suggest that menopause-related brain changes may contribute to increased vulnerability to Alzheimer's disease later in life. This could help explain why there's a higher prevalence of dementia observed in women.

We also investigated whether taking HRT post-menopause had any effect on health outcomes. Notably, HRT did not improve the reduction in brain grey matter.

In addition, we found that women using HRT showed higher levels of anxiety and depression compared to post-menopausal women who had never used HRT. However, further analyses indicated that these differences were already present. This suggested that pre-existing mental health problems may have influenced the decision to begin using HRT rather than these symptoms being caused by the medication itself.

One potential benefit of HRT use was noted in cognitive performance — particularly for psychomotor speed. Psychomotor slowing is a hallmark feature of aging.

Post-menopausal women who had never used HRT showed slower reaction times compared with both pre-menopausal women and post-menopausal women who had used HRT. This indicates that HRT helps to slow the menopause-related declines in psychomotor speed.

HRT and menopause

There's still much we don’t know about HRT — and more evidence on its benefits and risks are still needed.

Some studies report that those taking HRT have an increased dementia risk, while others suggest a decreased risk of dementia.

More research is also needed to understand the effects of HRT and how the different routes and dosages affect menopause symptoms. But according to one UK Biobank study of 538 women, the effects don't appear to differ — regardless of factors such as the formulation, route of administration and duration of use.

Importantly, however, it's difficult to establish whether women are actually receiving an effective dose. One in four women using the highest licensed dose of HRT still had low levels of estradiol (estrogen) — around 200 picomoles per liter. Older women and HRT patch users were more likely to have lower levels.

Optimal plasma levels to relieve menopause symptoms are between 220-550 picomoles per liter. This means that for 25% of the women in the study, HRT would not have had optimal benefit for menopause symptoms.

Considering that most women go through the menopause, it’s important to resolve the question of whether HRT is beneficial — including preventing brain grey matter volume reductions and reducing the risk of dementia. It will also be important to know what the best dose and route of administration are.

There is evidence to suggest healthy lifestyle habits may mitigate these menopause-related changes in brain health.

Our work and that of other research groups shows that a number of lifestyle habits can improve brain health, cognition and wellbeing, thereby reducing the risk of cognitive decline associated with aging and dementia. This includes regular exercise, engaging in cognitively challenging activities (such as learning a new language or playing chess), having a nutritious and balanced diet, getting the right amount of good-quality sleep and having strong social connections.

Research also shows regular physical activity can increase the size of the hippocampus, which may help mitigate some of the menopause-related reductions observed in this region.

Sleep is also critically important as it supports the consolidation of memories and helps clear toxic waste byproducts from the brain — processes that are essential for memory, brain health and immune function.

Having a healthy lifestyle may offer an accessible and effective strategy to promote brain health, cognitive reserve and resilience to stress during and after the menopause transition.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

A new study is the first to identify genetic variants linked with chromosomal abnormalities that can lead to pregnancy loss.

About half of pregnancy losses in the first trimester are caused by aneuploidy, a condition in which cells have an abnormal number of chromosomes. Studies show that aneuploidy is much more common in egg cells than in sperm cells and that it affects an increasing proportion of a person's eggs with age.

Aneuploidy in eggs can contribute to infertility and pregnancy loss in women, as well as genetic disorders in children, some of which can cause severe disability or death. But currently, little is understood about the individual factors linked to a greater risk of producing aneuploid eggs and, in turn, aneuploid embryos.

"I think that's a big blind spot for our field," said Rajiv McCoy, an associate professor of biology at Johns Hopkins University. McCoy and colleagues aimed to address this blind spot in a new study, published in January in the journal Nature.

They used clinical genetic testing data from over 139,000 embryos created for in vitro fertilization (IVF) to examine the relationship between maternal genetic variants and the incidence of aneuploid embryos. The dataset included 22,850 mothers, whose ages ranged from about 20 to nearly 56 years old. The average age was about 36 years old, around the age women's risk of producing aneuploid embryos sharply increases.

"We previously didn't have any very well-characterized associations between genetic variation in the mother's genome and risk of producing eggs with aneuploidy," McCoy told Live Science.

The researchers performed genome-wide association studies, meaning they looked for statistical links between gene variants carried by the study participants and certain traits — in this case, the incidence of aneuploidy. They also analyzed the transcriptome, meaning the RNA inside cells; this genetic cousin of DNA carries instructions for making proteins and can give a snapshot of which genes are active.

The strongest association identified was with specific versions of SMC1B, a gene for a key protein that helps hold the two halves of chromosomes together. Another significant association was drawn to C14orf39, which helps mediate important interactions between chromosomes as cells divide.

The study provides insight into aneuploidy's relationship to a process called "crossover recombination," in which chromosomes exchange chunks of DNA during the formation of an egg or sperm cell. McCoy's team observed that crossover count — the number of DNA exchanges that happen during this process — was lower in aneuploid embryos. That supported previous findings that linked errors in crossover recombination, which can cause issues with chromosome separation during cell division, to a greater likelihood of aneuploidy.

But the study also uncovered something new about this relationship: The genetic variants tied to aneuploidy risk are also involved in crossover recombination. "The same machinery that's influencing recombination is the machinery that's influencing risk of producing these aneuploidies," McCoy said.

"This helps us understand how all of these traits are tied together," said Shai Carmi, a professor of computational and statistical genetics at the Hebrew University of Jerusalem who was not involved in the research. "What are the risk factors that make some women have more aneuploidy and, therefore, lower fertility?"

Even for those not experiencing infertility, pregnancy loss is incredibly common.

"About 10% to 20% of clinically recognized pregnancies end in miscarriage," McCoy said. "But we actually think that about half of all conceptions are lost before birth, many of them very early on in development."

In uncovering the shared genetic basis underlying both crossover recombination and aneuploidy, this study underscores the fact that crossovers play an essential role in ensuring that the correct number of chromosomes end up in a given egg, so that an eventual pregnancy is viable.

Because each genetic variant tied to aneuploidy can explain only a small part of an individual's overall risk, it's too early for these findings to be applied to actual patients. Still, "that doesn't mean that it's not possible, in the future, to get better predictions of people's risk," McCoy said. "And this provides one clue as to what we should be looking for."

These findings could also serve as a starting point for further research aimed at developing therapies and diagnostics to help reduce pregnancy loss. That said, McCoy also thinks simply knowing more about the mechanisms behind pregnancy loss is meaningful in itself.

"I personally think that the value of this study is more fundamental," he said. "It's helping us understand who we are as humans."

A figure commonly cited to compare the risks of pregnancy and abortion in the U.S. could be grossly underestimating the risk of death from pregnancy, according to a new analysis.

The research, published Jan. 21 in the journal JAMA Network Open, suggests that the risk of pregnancy-related death might be at least 44 times higher than the risk of abortion-related death. Previously, pregnancy was estimated to carry a roughly 14 times higher risk of death, making the new estimate over three times higher.

"It was already fairly alarming that you face a 14-times greater risk of death from continuing a pregnancy [compared to getting an abortion]," lead study author Maria Steenland, an assistant professor at the University of Maryland's School of Public Health, told Live Science. "But the statistics we report here suggest that this risk is really much, much higher."

The updated figure could help steer conversations surrounding abortion access in the United States, the study authors hope.

"What we're showing in the paper is quite simple: Taking away the option to end a pregnancy exposes people to a much greater risk of death," she said.

A stat based on 20-year old data

When tracing the original estimate of risk back to its source, Steenland and her colleagues realized the statistic was based on a single 2012 study using data that is now almost 20 years old.

That study looked at the Centers for Disease Control and Prevention's (CDC) Pregnancy Mortality Surveillance System for records of deaths that had happened within a year of birth; the data covered about 32,350,000 live births in the United States, between 1998 and 2005. Those data were compared with records of abortions-related deaths collected by the CDC across those same years, which totaled to 65. That was out of about 10 million total abortions, according to the Guttmacher Institute, a research nonprofit that monitors abortion surveillance data in the U.S. and globally.

"You don't have to know a lot about maternal health in the U.S. to think, 'Perhaps that statistic has changed since then,'" Steenland said. A quick "back of the envelope" calculation tipped the researchers off that this ratio might now be critically outdated, she added.

To establish an updated risk ratio, the study authors scoured national databases to pool stats collected between 2018 and 2021. The databases included the CDC's National Vital Statistics System, which provided the total number of births and pregnancy-related deaths in the U.S., out to a year postpartum. The CDC's Pregnancy Mortality Surveillance System documented the number of abortion-related deaths per year, while the total number of abortions per year was obtained from the Guttmacher Institute.

The study authors included both live births and stillbirths in the total number of births, which was not done in the 2012 study. This enabled the researchers to roughly approximate the total number of pregnancies in the U.S., which isn't currently tracked.

While this metric is the next best thing to a count of pregnancies, it still misses some, such as ectopic pregnancies and miscarriages, Steenland noted. Since they couldn't confidently count those earlier-stage pregnancies, the researchers also excluded deaths that occurred in those stages from the overall count, she said; they wouldn't have been able to generate an accurate risk ratio with the missing data.

The study found an annual average of 32.3 maternal deaths per 100,000 births in the U.S. between 2018 and 2021. That included at least 3,662 pregnancy-related deaths over the four years, out of about 15 million births. For comparison, that's at least twice the pregnancy-related mortality rate reported in the 2012 study, which ranged from 8.8 to 14.5 per 100,000 live births.

The increased rate may come down to improved tracking of pregnancy-related deaths, the study authors suggested. Notably, a 2003 revision to U.S. death certificates, which was fully implemented in 2018, introduced a "pregnancy" checkbox.

The risk of abortion-related death reported in the new study remained very low, with 17 abortion-related deaths documented between 2018 and 2021 out of more than 3.5 million documented abortions in the U.S. That put the abortion-related mortality rate at about 0.46 deaths per 100,000 abortions, which is marginally lower than the figure of 0.60 per 100,000 abortions reported in the 2012 paper.

A higher death toll linked with pregnancy

Taken together, the 2026 analysis suggests that the risk of death related to pregnancy is at least about 44 times higher than the mortality risk linked to abortion — a figure that towers over the commonly reported statistic suggesting pregnancy is 14 times more likely to result in death than an abortion is.

But, of course, this new figure captures only part of the story, Stephen Burgess, a statistician at the University of Cambridge who was not involved in the study, told Live Science.

The risk of death from pregnancy is known to vary by the age and socioeconomic status of the pregnant person, as well as their access to health care, he noted. Those factors can make a big difference in how well a pregnancy goes and whether it leads to complications that can result in death. The risk ratio itself is also "highly dependent" on the dataset being used to capture abortion rates across the U.S., he noted.

Of note, the Guttmacher Institute did not report the number of abortions in the U.S. in 2021. In the new study, the study authors duplicated the stats from 2020 for the number of abortions in the U.S. in 2021, making the assumption that they were about the same.

Burgess welcomed the new work, saying it provides a more accurate measure of the mortality risk tied to pregnancy, including postpartum care. However, he questioned whether the figure would be "useful in helping either mothers or policymakers to make good decisions."

But for Steenland, the overarching message is clear.

"I think people should know what they're facing, and policymakers should be required to try to make it possible for everyone to access the highest-quality maternity care, to have the best outcomes that they possibly could have," she said.

Maternal care in the U.S. has been on a steady decline in recent decades, with maternal deaths increasing consistently since the 2000s, per a 2024 report from The Commonwealth Fund. Most of these deaths are likely preventable, the report said.

The 2022 U.S. Supreme Court ruling on Dobbs v. Jackson Women's Health Organization — which overturned Roe v. Wade — also opened the door for states to ban or heavily restrict abortion. The impacts of that decision are already being felt and are anticipated to prevent improvements in the maternal mortality rate in the near future. This disparity is most keenly felt by certain populations, with Black mothers being 3.3 times more likely to die in states that restrict access to abortion than white mothers in those states.

A recent study also suggests that infant deaths have been on the rise since the abortion bans went into effect.

Steenland noted that going forward, it might be difficult to track pregnancy-related deaths, as "it's very unlikely that CDC will continue to release abortion related mortality statistics," following large cuts to the CDC's Division of Reproductive Health staff in 2025.

"That limitation, along with other reductions and publicly available information that can be used to measure these outcomes," she said, "will limit for sure what we can know about how the ratio has changed or will have changed."

This article is for informational purposes only and is not meant to offer medical advice.

A woman in California was scheduled to have a large cyst removed and tested positive on a routine pregnancy test just prior to the procedure. She would soon learn that she actually had a full-term baby tucked away in her abdomen, hidden behind the cyst.

Suze Lopez, a 41-year-old emergency room nurse from Bakersfield, underwent a procedure to have both the cyst removed and her baby delivered at the same time. The effort involved about 30 medical professionals at Cedars-Sinai Medical Center in Los Angeles.

Lopez began hemorrhaging after the baby was delivered but was stabilized by the medical team, who used 11 units of blood to do so, according to a statement from Cedars-Sinai. (For context, a typical blood donation is about one pint of blood, which is one unit.)

The baby, who weighed 8 pounds (3.6 kilograms) at birth and had a full head of hair, was quickly transferred to the neonatal intensive care unit (NICU) after birth. All things considered, he was remarkably healthy, his physicians said.

"I was amazed by this little guy," Dr. Sara Dayanim, a neonatologist with Cedars-Sinai Guerin Children's, said in a video accompanying the announcement. "He's defied all odds," she said.

How the pregnancy went undetected

The baby, named Ryu, was discovered because Lopez was scheduled to have a 22-pound (9.9 kg) ovarian cyst removed. The cyst was noncancerous, but it had been growing for years by the time Lopez was scheduled to undergo the surgery.

Lopez was used to experiencing irregular periods and abdominal discomfort, so she didn't expect to get a positive result on the pregnancy test prior to the surgery. She surprised her husband Andrew with news of the pregnancy while at a Dodgers baseball game in Los Angeles; the pair snapped a selfie together while holding up a Dodgers-branded onesie.

However, later at the game, Lopez started to have intense abdominal pain, and they immediately went to Cedars-Sinai.

Lopez arrived at the hospital with very high blood pressure, and as medical staff set about treating it, they also ran blood work and body scans, including an MRI and ultrasound. That's when they discovered that Lopez was carrying a rare abdominal ectopic pregnancy. The baby was situated near the liver, with his back half resting on top of the uterus.

"It was the baby growing in her abdomen behind the mass that was pushing everything out," Dr. John Ozimek, medical director of Labor and Delivery and the Maternal-Fetal Care Unit at Cedars-Sinai, said in the video. "So that's the reason she didn't know she was pregnant."

He added that "a pregnancy this far outside of the uterus that is living is pretty much unprecedented."

Ectopic pregnancies occur outside the uterus and account for roughly 2% of all pregnancies. All forms of ectopic pregnancy, in any location in the body, are life-threatening, as they can rupture organs and cause catastrophic bleeding and, potentially, shock due to blood loss. Ectopic pregnancies cannot be transferred into the uterus, and as such, medical guidance is to treat the condition by ending the pregnancy, either with medication or surgery.

The vast majority of ectopic pregnancies — about 95% — occur in a fallopian tube, a tube that shuttles eggs from an ovary to the uterus. Abdominal ectopic pregnancies, by comparison, occur in only about 1% of ectopic pregnancy cases.

If an ectopic pregnancy escapes notice — as in this case — it's very improbable that the fetus would develop normally outside the uterus. Thus, fetal death is likely.

That said, the medical literature includes a handful of unusual cases in which abdominal ectopic pregnancies were discovered very late in gestation and ultimately resulted in the birth of healthy babies.

In Lopez's case, "we had to figure out how to deliver the baby with a placenta and its blood vessels attached in the abdomen, remove the very large ovarian mass and do everything we could to save mom and this child," Dr. Michael Manuel, a gynecological oncologist at Providence Cedars-Sinai Tarzana Medical Center, said in the statement. And in the end, they were successful.

Lopez, who has a teenage daughter, had been hoping for a second pregnancy for years.

"I could not believe that after 17 years of praying, and trying, for a second child, that I was actually pregnant," she said in the statement. "I appreciate every little thing. Everything. Every day is a gift and I'm never going to waste it."

This article is for informational purposes only and is not meant to offer medical advice.

Scientists have taken an important step toward understanding why human eggs grow more prone to chromosomal errors as they age and whether that decline could be circumvented someday.

The research, published in November in the journal Nature Aging, introduces a new tool that enables scientists to replicate changes seen in eggs during the aging process. The technique, which uses mouse egg cells, doesn't require researchers to wait for the mice to age or to collect aged human eggs for study, and it enables them to zero in on different forces that might contribute to an egg's decline.

"They have created a tool that's going to allow them to unpick this really beautifully," said Bettina Mihalas, a postdoctoral fellow at The University of New South Wales in Sydney who was not involved in the research. "Being able to tease these mechanisms apart gives you a better scope of what's going on, and allows you to more [precisely] intervene," Mihalas, who is studying strategies to improve fertility in aging, told Live Science.

This research is in its early days, but eventually, the study authors hope it could help extend the reproductive windows of women who plan to have children later in life.

"Female reproductive aging is a major source of inequity," said senior study author Binyam Mogessie, an assistant professor at the Yale University School of Medicine. "Women have to make choices men don't have to make" when it comes to weighing when to start a family. Notably, the rate of under-30 births is now trending down as over-30 births trend up in the U.S. In short, more women are having babies at older ages, when the rate of chromosomal abnormalities begins to rise.

"Even if we can extend this reproductive window by three years, it would be so consequential to the lives of so many people," Mogessie told Live Science.

A model of aging eggs

Women are born with all the egg cells they'll ever carry, and over time, those eggs are released via the menstrual cycle. Eggs that have yet to be released hang out in the ovaries, where many will stay for decades.

Around age 30, this waiting egg supply shows a sharp uptick in aneuploidy risk, meaning the eggs are more likely to carry an abnormal number of chromosomes — either more or less than 46. Studies show that the risk of egg aneuploidy grows almost exponentially after age 35, and then jumps again at 40 and at 45. These chromosomal abnormalities can contribute to infertility and pregnancy loss in women, as well as genetic disorders in children, some of which can cause severe disability or death.

Scientists are still unsure why aneuploidy risk goes up so much with age. "The leading theory is that the forces that hold these chromosomes together, before they are separated at fertilization, those forces are failing progressively with age," Mogessie said.

At various points in an egg's cell cycle, each of its chromosomes contains two "sister chromatids" held together by molecular glue, and those sisters later get pulled apart. That glue is known to weaken with age and thus lead to chromatid separation issues that contribute to aneuploidy. But that doesn't tell the whole story; it doesn't explain why we see a sharp rise in chromosomal errors starting around age 30, Mogessie said.

To investigate this mystery, the researchers developed an experimental setup to trigger "aging-like" changes in eggs and watch how the eggs changed afterward, using high-resolution time-lapse microscopy. A key part of the model was the use of the gene-editing system CRISPR to tweak a critical component of the molecular glue that holds chromosomes together: a protein called REC8.

This tweak added a switch to REC8, and once that switch was toggled "on," the protein would degrade. Using this system, the scientists could tightly control the degree of REC8 breakdown in an egg, simulating what would happen naturally during aging.

"In animals, it can take years; in humans, it can take decades for these processes to arise," Mogessie said. But the new technique "allows us to do this within 60 to 90 minutes."

Previously, Mogessie and collaborators had used antibodies to mess with REC8 in a similar way, but this involved injecting the antibodies into delicate egg cells — a finicky and labor-intensive process — and the degree of degradation was difficult to control, Mihalas noted. Some benefits of the new system are that you avoid injecting the eggs and can tune REC8 levels much more precisely. "It is quite elegant," she said.

Paving the way to future treatments

The team demonstrated that degrading REC8 to varying degrees led to errors in chromosome splitting and to aneuploidy, as you'd expect to see in naturally aged eggs. This also enabled them to pinpoint a specific threshold of REC8 loss at which the rate of errors suddenly spiked.

While the loss of REC8 could trigger these issues, scientists know that eggs decline in additional ways with age. To model this, the team messed with other proteins involved in holding chromosomes together, as well as with filaments that pull them apart when the time is right. These perturbations boosted the rate of chromosomal errors beyond what was seen with REC8 loss alone.

Taken together, these results suggest that the breakdown of chromosomes' molecular glue likely sets the stage for aneuploidy. But the sudden spike seen in people in their 30s and 40s likely stems from the "synergistic failure" of multiple parts of this chromosome-separating machinery, the team said.

More research is needed to fully understand the impact of aging on eggs, but the new model should enable such work to be done. "The mouse model provides consistency," Mihalas noted. Given the ethical challenges and limitations of working with human eggs, "it's the best model we have," Mihalas added.

In the long run, the model could be used to screen for and test the effects of potential treatments. There may be a way to turn back the clock and help eggs to reliably divide with fewer chromosomal errors, as they would have at younger ages.

"It really does set the scene for preventive measures aimed at improving the quality of eggs, at least in an IVF [in vitro fertilization] clinic setting," Mogessie said. "I think that would have a huge impact."

This article is for informational purposes only and is not meant to offer medical advice.

Ozempic and similar drugs are not recommended for use in pregnancy, but stopping the medications before conception may also come with some risks, new data suggest.

These data should be interpreted as an early signal that warrants further investigation, a researcher involved in the study told Live Science.

The analysis had key limitations. The women who did and did not use the weight-management drugs may not have been completely comparable, and the study was not designed to capture potential benefits of taking Ozempic or a similar drug before pregnancy.

"We don't know if there's a benefit, or if there's increased risk, if you get to pregnancy at a lower weight and then come off the medication," said study first author Dr. Jacqueline Maya, a pediatric endocrinologist and physician-investigator at Massachusetts General Hospital who studies how events in pregnancy impact the health of both mother and child.

For now, Maya said the new study's results are a "heads up" for doctors. "We just need to monitor [these patients] closely, because there were some obstetric outcomes that we need to keep an eye on," she told Live Science.

An understudied population

Drugs like Ozempic, Wegovy and Zepbound are "glucagon-like peptide-1 receptor agonists," or GLP-1s, for short. GLP-1s regulate weight and improve blood sugar through several mechanisms, such as by slowing down digestion and altering how the brain sends "hunger signals." The drugs have been tied to dozens of knock-on benefits, including a lower risk of both heart attack and dangerous blood clots.

But studies in mice and rabbits suggest that the drugs may raise the risk of birth defects and pregnancy loss and restrict fetal growth. "So, the recommendation currently is to stop the medication prior to conception," Maya said.

This recommendation means that there's a population of women who stop using GLP-1s before pregnancy, raising questions about whether that can cause any negative effects. In the general population prescribed GLP-1s, stopping the medications comes with a rebound in weight gain and related metrics, such as blood pressure, cholesterol and blood sugar. But these effects haven't been studied much in pregnancy.

"To date, only 1 other study has examined gestational weight gain after GLP-1RA use," and "only a handful" have looked at links between the drugs and other adverse pregnancy outcomes, epidemiologists Carolyn Cesta, Jennifer Hutcheon and Kari Johansson wrote in a commentary of the new research.

To help fill this gap, the researchers looked back at hundreds of singleton pregnancies delivered in the Mass General Brigham health system between 2016 and 2025. They focused on about 450 pregnancies in which mothers used GLP-1s between three years before and 90 days after conception. About 50% stopped taking the medications within six months of conception, about 34% stopped earlier than that, and 17% stopped after conception.

Just prior to pregnancy, the average BMI of these mothers was about 36, which is categorized as obese. The researchers compared these GLP-treated individuals against mothers who had never used the medications but also had BMIs of about 36 before pregnancy. The full range of BMIs in both groups ran from "healthy" to "severely obese," with similar proportions of people in each category in each group.

Those who had taken and then stopped GLP-1s had an increased risk of preterm delivery, gestational diabetes, and hypertensive disorders of pregnancy, such as gestational high blood pressure and preeclampsia, the analysis found. Additionally, the GLP-1-treated group gained more weight during pregnancy — about 30 pounds (13.7 kilograms), on average, compared with an average of 23 pounds (10.5 kg) for the comparison group.

And notably, more people in the GLP-1-treated group had "excessive gestational weight gain," which is associated with health risks for both the mother and the baby. The amount of weight gain that's considered "excessive" varies depending on the individual's pre-pregnancy BMI, according to guidelines from the National Academy of Medicine. About 65% of the GLP-treated group had "excessive" weight gain, compared with 49% of the comparison group.

Within the treated group, the timing of the GLP-1 stoppage didn't seem to have a huge effect on the results. "We expected, I think, a more pronounced change, but our results were pretty similar," Maya said. It may be that excess weight gain drove the other pregnancy outcomes observed, but the current data can't demonstrate that for certain, she noted.

Questions remain

One significant limitation of the study was that the team compared people who had taken GLP-1s with people of similar body mass who had never been on the drugs. In other words, the researchers looked at the treated group only after they were exposed to GLP-1s, when their BMIs had likely fallen lower than their pre-prescription weights, the commentary writers noted.

In the future, the researchers also want to take people's pre-GLP weights into account and find a comparison group with comparable baseline BMIs, Maya said. These data, which they're working to gather now, would help contextualize whether there are any benefits of using the drugs to lose weight prior to conception, even if you then have to come off the drugs during pregnancy.

The commentary authors added that some of the new study's results appear to contradict other research. For instance, some studies have linked GLP-1 use to a lower risk of hypertensive disorders of pregnancy. But that may be because those previous studies included a higher proportion of people who were prescribed GLP-1s for diabetes, while the new study skewed toward people who specifically took the medicines for obesity.

Like the new study, this previous work compared GLP-1 users with "women with similar BMI near the start of pregnancy but with no history of GLP-1RA use," the commentary authors added. This might be common across studies due to databases having a "paucity of data" on patients' pre-treatment BMIs, and the fact that it's challenging to then link that BMI data to prescription and pregnancy records.

But these data gaps further underscore the need to study this population, as currently, there is "limited or no clinical guidance" on the use of GLP-1s prior to conception, the commentary authors wrote. The new research, published Monday (Nov. 24) in JAMA, begins to close the gap, but more studies are needed to understand the medications' pros and cons for people planning to conceive.

"It is critical that we strive to generate the evidence needed both to inform obstetric care and guide treatment initiation decisions," the commentary authors concluded.

As is common in drug research, initial trials of GLP-1s excluded people who said they were planning to conceive, but that population still uses these medications. "That's how this research unfolds," Maya said, "and then slowly, we come in and advocate for some of these vulnerable groups that weren't included in the initial studies."

This article is for informational purposes only and is not meant to offer medical advice.

Like many first-time mothers, Lisette Lopez-Rose thought childbirth would usher in a time of joy. Instead, she had panic attacks as she imagined that something bad was going to happen to her baby, and she felt weighed down by a sadness that wouldn't lift. The San Francisco Bay Area mother knew her extreme emotions weren't normal, but she was afraid to tell her obstetrician. What if they took her baby away?

At about six months postpartum, she discovered an online network of women with similar experiences and ultimately opened up to her primary care doctor. "About two months after I started medication, I started to feel like I was coming out of a deep hole and seeing light again," she says. Today, Lopez-Rose works at Postpartum Support International, coordinating volunteers to help new mothers form online connections.

About one in eight US women go through a period of postpartum depression, making it among the most common complications of childbirth. It typically occurs in the first few weeks after delivery, when there's a sudden drop in the reproductive hormones estrogen and progesterone. As scientists unravel chemical and genetic changes caused by those shifting hormones, they are discovering new ways to diagnose and treat postpartum depression, and even ways to identify who is at risk for it.

The first-ever drug for postpartum depression, containing a derivative of progesterone, received US Food and Drug Administration approval in 2019. That marked a new approach to the disorder. This winter, in another major advance, a San Diego-based startup company will launch a blood test that predicts a pregnant woman's risk of postpartum depression with more than 80 percent accuracy.

The product, called myLuma, will be the first commercially available test to use biomarkers — molecules in the body, in this case the blood — to predict onset of a psychiatric disorder, much in the way that blood tests can detect signs of diseases like cancer and diabetes. Pregnant women who learn they are at risk for postpartum depression could take preventive steps such as taking antidepressants after childbirth or arranging for extra support.

A blood test could reduce the stigma that keeps many women from seeking help, says Jennifer Payne, a reproductive psychiatrist at the University of Virginia in Charlottesville and a lead investigator on the studies that led to the new test. She is a founder and member of the scientific advisory board for the company that makes myLuma, Dionysus Health.

"If we have a blood test, it brings psychiatry down to the level of biology, which I think your average person can understand as something that needs treatment and that isn't just in somebody's head," she says.

Unpredictable effects of hormones

Payne was a fellow at the National Institute of Mental Health in 2001 when she became intrigued by postpartum depression as a window into the onset of mood disorders. That led her to a key question: Why does the sudden drop in hormones after childbirth greatly affect some women but not others? While it's not uncommon for women to experience transient feelings of anxiety and sadness within days of giving birth, only in some does a deeper and more persistent depression take hold.

As Payne's research evolved, she teamed up with Zachary Kaminsky, then a colleague at Johns Hopkins University, who studied the effects of estrogen on mouse brains. Kaminsky is an epigeneticist: He researches how small chemicals called methyl groups can attach to genes and affect how active they are. Environmental factors from pollution to nutrition can affect the extent of this reversible methylation.

By comparing female mice given high levels of estrogen to those without it, Kaminsky found that estrogen caused specific gene methylation patterns inside cells in the hippocampus, a part of the brain that helps control mood. Those findings suggested what to look for in blood samples Payne had collected from 51 women with a history of mood disorders. The women had been tracked throughout their pregnancies and afterward, with some developing postpartum depression within four weeks of childbirth.

Two estrogen-sensitive genes emerged from the research — HP1BP3  and TTC9B. More than 80 percent of the women who had postpartum depression showed a distinctive pattern of greater methylation on one gene and less methylation on the other. What's more, the changes in the genes could be detected throughout each trimester of pregnancy, says Kaminsky, now at the University of Ottawa Institute of Mental Health Research at the Royal; he also is a cofounder of Dionysus. In other words, even early in pregnancy, Kaminsky says, "you can predict the women that are going to get postpartum depression."

Kaminsky, Payne and collaborators repeatedly replicated those findings. As reported in a 2016 paper in Neuropharmacology, they found that through the methylation patterns of those genes, they could correctly predict more than 80 percent of the cases of postpartum depression in 240 pregnant women who had no history of psychiatric disorders. In another collaboration published in 2020 in Psychiatry Research, scientists at Johns Hopkins, Emory University and the University of California, Irvine, including Payne and Kaminsky, tested blood samples from 285 pregnant women and also confirmed the findings.

That epigenetic research forms the basis of the myLuma test, which also incorporates additional biomarkers that improve its accuracy, says Kaminsky. Beginning in January 2026, it is expected to become available at some doctors' offices in three states: Florida, Texas and California. Though it isn't yet FDA-approved, doctors are permitted to use such lab tests to help make clinical decisions.

Zeroing in on steroids

Not everyone with postpartum depression has these epigenetic changes, so Payne and other researchers continue to hunt for other biomarkers to understand how hormonal changes trigger postpartum depression. They are zeroing in, for example, on neuroactive steroids, which the body makes from molecules like progesterone in the brain and other tissues.

One of those metabolites, called allopregnanolone, has a calming effect — it affects a receptor in the brain called GABA-A, which is known to be involved in stress reduction. Allopregnanolone rises during pregnancy and drops swiftly after delivery. Another neuroactive steroid, pregnanolone, has similar properties. A third, isoallopregnanolone, tamps down the antidepressant effect of allopregnanolone, increasing feelings of stress.

In a study of 136 pregnant women published in 2025 in the journal Neuropsychopharmacology, women with an imbalance in pregnanolone and isoallopregnanolone during pregnancy were more likely to develop postpartum depression. Measuring the ratio of these chemicals in the blood could be another way to predict postpartum depression, says reproductive psychiatrist Lauren M. Osborne of Weill Cornell Medicine in New York City, who co-led the study with Payne.

Allopregnanolone, meanwhile, has already proved to be a valuable tool for treatment. A synthetic version called brexanolone was developed by Cambridge, Massachusetts-based Sage Therapeutics and FDA-approved in 2019 — the first drug approved specifically for postpartum depression. Originally provided via IV infusion, it has been replaced by an oral version, zuranolone, which was FDA-approved in 2023.

These are "transformative therapies" because they work rapidly, write the authors of a 2025 article in the Annual Review of Medicine. Women at high risk of postpartum depression might even benefit from proactively taking zuranolone, though that hasn't yet been tested, says article coauthor Samantha Meltzer-Brody, a reproductive psychiatrist at the University of North Carolina who was an academic principal investigator in studies of brexanolone and an investigator in zuranolone trials.

The availability of a blood test, she adds, "opens up that entire line of questioning on how do you get ahead of it, so you don't have to wait until someone starts suffering?"

There are other possible targets for a postpartum depression test. In a 2022 article in Molecular Psychiatry, Johns Hopkins neuroscientist Sarven Sabunciyan, with Osborne, Payne and Morgan Sherer, then an immunologist at Johns Hopkins, described a small study in which the types of RNA carried through blood in fatty bubbles were different in women who developed postpartum depression — both in pregnancy and afterwards. In particular, there was a decrease in kinds of RNA related to autophagy — the cleansing of debris from cells. Autophagy has been linked to other psychiatric disorders.

In another potential lead, Eynav Accortt, a clinical psychologist specializing in perinatal mental health at Cedars-Sinai Medical Center in Los Angeles, found a pattern of altered proteins in plasma samples of women who developed perinatal mood and anxiety disorders, a group of conditions that includes postpartum depression. This included proteins involved in neuron function and in inflammation, which is known to play a role in depression.

As researchers continue to explore these possibilities, Payne is leading a large clinical trial that will provide more detailed information on the predictive value of the myLuma test. For example, it will explore the rates of false positives (women who are identified as at-risk who do not develop postpartum depression) and false negatives (women who develop postpartum depression but weren't identified by the test). That is a necessary step toward FDA approval, which could make the test available directly to pregnant women.

Lopez-Rose remembers how scared she felt in the months after her daughter was born. In those dark times, she quit her job, barely slept and was overwhelmed by negative thoughts. She had many self-doubts, but she now knows that reaching out for help was a sign that she was a good mother.

Today, her daughter is four — and thriving, as is Lopez-Rose. But a blood test, she says, would have warned her of what to look out for, "instead of it being so shocking when I was going through my depression."

This article originally appeared in Knowable Magazine, a nonprofit publication dedicated to making scientific knowledge accessible to all. Sign up for Knowable Magazine’s newsletter.

People who are pregnant or lactating should not use cannabis, newly updated guidelines from the American College of Obstetricians and Gynecologists (ACOG) stress.

The professional group, which in a 2017 report already encouraged OB-GYNs to advise their patients against cannabis use during pregnancy, now recommends that clinicians systematically ask about, or "screen for", cannabis use by their patients before, during and after pregnancy. The updated guidelines, published in September, also say clinicians should educate their patients about the drug's potential risks.

"Just like we talk about tobacco use in pregnancy or alcohol use in pregnancy, cannabis use in pregnancy should be part of the natural conversation," said Dr. Amy Valent, an assistant professor of obstetrics and gynecology at the Oregon Health and Science University (OHSU) School of Medicine who participated in crafting the recommendations.

ACOG recommends universal screening for cannabis through interviews, self-reports and other validated tools, but the professional group advises against biological testing, which uses hair or urine samples to detect cannabis use. Historically, biological testing has disproportionately affected minorities.

"Black patients screen positive for substance use disorders at the same rate as White patients yet are 4-10 times more likely to have a positive drug screen result reported to child protective services," the guidelines emphasized.

Cannabis use on the rise

In recent years, more and more pregnant individuals have turned to cannabis as a "natural" way to alleviate symptoms such as nausea and vomiting. Some also use cannabis to help them cope with the stress and anxiety often associated with pregnancy.

Between 2002 and 2020, self-reported cannabis use has more than tripled among pregnant individuals in the U.S., according to a study published in 2022 that used data from the National Survey on Drug Use and Health. In 2002, 1.5% of pregnant individuals reported using cannabis without alcohol, compared to 5.4% in 2020.

In addition, various studies show that, in the U.S., about 4% to 16% of people use the drug while pregnant.

"With the legalization of it [cannabis] in a lot of states, people are perceiving the risk to be very low," Dr. Alta DeRoo, a board-certified addiction medicine physician, obstetrician-gynecologist and the chief medical officer at the Hazelden Betty Ford Foundation who did help write the guidelines, told Live Science.

However, ACOG points out that there are no uses for cannabis during pregnancy that are backed by medical science and that it can have serious health consequences for newborns.

Growing evidence of serious health outcomes

The updated guidelines are based on a growing body of evidence that links cannabis use around the time of conception and throughout pregnancy with adverse outcomes, including preterm birth, low birth weight and higher rates of neonatal intensive care unit (NICU) admissions.

In addition, evidence suggests cannabis use during pregnancy and lactation could raise the risk of long-term health effects for children, including neurodevelopmental conditions like ADHD.

Studies have shown that THC, the main psychoactive ingredient in cannabis, can cross the placenta and transfer into breast milk. Cannabinoid receptors — "docking stations" that body-made cannabinoids and cannabinoids from plants can land on — are present in the fetus as early as five weeks of gestation, before a person might know they're pregnant.

"Cannabis exposure during pregnancy significantly decreases placental bloodflow, oxygen availability to the baby and causes changes in the placenta that are similar to placental insufficiency or dysfunction," said Dr. Jamie Lo, an associate professor of obstetrics and gynecology at the OHSU School of Medicine who was not involved in writing the guidelines. This placental dysfunction has been documented in both animal and human studies.

Researchers don't know whether there could be a safe amount of cannabis use during pregnancy.

"I think it's very similar to alcohol use, right? We know that there's a specific syndrome that's associated with alcohol use disorder in pregnancy, but we don't actually know if there's a 'safe amount," Valent said. "Therefore, we definitely know that there's harm with alcohol use in pregnancy, but we don't know to what degree people are going to be more or less vulnerable. And so we don't recommend alcohol use in pregnancy."

Cannabis products are not regulated by the Food and Drug Administration in the same way that pharmaceutical drugs are, she added. As such, they can be subject to cross contamination and other quality control issues. In light of that, Valent recommends that pregnant people stay away from all cannabis products, including CBD, the nonpsychoactive ingredient in cannabis.

Educating patients

In its recent clinical consensus, ACOG provided OB-GYNs with more information about the ways they can inform their patients about the risks associated with cannabis use during pregnancy and lactation, as well as better understand the reasons driving their personal use of the drug. ACOG also advised clinicians on how to guide patients toward safer alternatives that fit their needs.

"Parents want the best things for their children, and they're not trying to do something that might harm their children," Lo said. Many pregnant people who use cannabis likely do so "because they just don't know" the risks, she told Live Science. "And for the longest time, we didn't have great data."

Lo added that there's been a "significant surge of newer literature" over the past few years showing the same adverse outcomes associated with the use of cannabis during pregnancy. The new guidelines use stronger language that "gives the healthcare provider tools to actually feel like they're supported by evidence and a [professional] society in their recommendations," she added. "It's not just their personal opinion."

Valent said she hopes the new guidelines will help raise awareness and spark conversations between clinicians and patients.

"Communication is really powerful between a provider and their patient," she said. "Being able to support our patients and make sure that they feel supported along that path to cessation [stopping cannabis use] is really important."

This article is for informational purposes only and is not meant to offer medical advice.

Scientists have created human eggs in the lab using a similar process to the one used to clone the famous Dolly the sheep, then used in vitro fertilization (IVF) to turn them into embryos.

Although this method is far from being used in a clinical setting, the hope is that it could eventually pave the way to new fertility treatments.

"In addition to offering hope for millions of people with infertility due to lack of eggs or sperm, this method would allow for the possibility of same-sex couples to have a child genetically related to both partners," study co-author Dr. Paula Amato, a professor of obstetrics and gynecology in the Oregon Health & Science University (OHSU) School of Medicine, said in a statement.

The proof-of-concept experiment was described Tuesday (Sept. 30) in the journal Nature Communications.

The egg-making process involved removing the nucleus from an existing human egg cell and swapping it out for a nucleus from a human skin cell. This first step, called somatic cell nuclear transfer, has been used to clone a variety of animals, including Dolly.

But the OHSU researchers aimed to make a functional egg, not a clone, and eggs carry half the chromosomes as nonreproductive cells in the body do. During fertilization, an egg's 23 chromosomes combine with 23 chromosomes from a sperm cell, resulting in a total of 46. To prompt their makeshift eggs to shed half their chromosomes, the scientists applied an electrical pulse and a drug called roscovitine, which messes with enzymes that regulate the cell cycle, the process by which cells divide.

This experiment ultimately resulted in 82 egg cells that were then fertilized with sperm via in vitro fertilization (IVF), according to the statement. However, the fertilization step isn't yet foolproof — only around 9% made it to the "blastocyst" stage. At that point, the egg has divided to form a hollow sphere of cells that could be introduced to the womb via IVF.

Most of the eggs fertilized in the study didn't make it to the blastocyst stage, and in fact, only divided enough times to produce four to eight cells overall.

The "modest" blastocyst development rate likely stems from two factors, the study authors wrote in their paper. For starters, chromosomal abnormalities likely stopped the fertilized eggs from dividing further. And second, the genes swapped in from skin cells likely weren't successfully reprogrammed to sustain embryonic development. In other words, in some ways, the genes were still activating as if they were in skin cells, not the cells that form early in development.

It's unclear which issue presented the bigger problem in this study, but it's likely both factors contributed, the authors wrote.

None of the eggs that made it to the blastocyst stage were grown any further, and because they too bore chromosomal abnormalities, it's unlikely they would have been suitable for use in IVF, the researchers noted. These abnormalities included having too many or too few chromosomes, although on average they ended up with 46. Some eggs also carried multiple copies of the same chromosome or were missing certain chromosomes altogether.

So for now, the technique "is too inefficient and high risk to apply immediately to clinical application," Katsuhiko Hayashi, a stem cell researcher at the University of Osaka who was not involved in the study, told Science News.

The study authors also noted that "at this stage it remains just a proof of concept and further research is required to ensure efficacy and safety before future clinical applications."

Looking forward, the team plans to research how to better orchestrate the halving and then doubling of chromosomes within the egg. The goal would be to better capture what happens in a natural human pregnancy so that the right chromosomes are lost in the initial halving and then properly paired up with new chromosomes during fertilization.

If someday the technique can be refined for use in fertility treatment, however, it does raise ethical questions, experts told NPR. For instance, people could feasibly gather skin cells from others — including celebrities — without their knowledge and make functional eggs with them, Ronald Green, a bioethicist at Dartmouth College, told NPR. "It's a theoretical possibility, but not crazy," he said.

Other labs are working on different approaches to making eggs in the lab. Some have used stem cells to grow the eggs, either starting with stem cells or with adult cells that they then reverted back into stem cells. This approach has shown some success in mouse experiments but progress on the human front has been slower.

Pronatalism — the belief that low birth rates are a problem that must be reversed — is having a moment in the U.S.

As birth rates decline in the U.S. and throughout the world, voices from Silicon Valley to the White House are raising concerns about what they say could be the calamitous effects of steep population decline on the economy. The Trump administration has said it is seeking ideas on how to encourage Americans to have more children as the U.S. experiences its lowest total fertility rate in history, down about 25% since 2007.

As demographers who study fertility, family behaviors and childbearing intentions, we can say with certainty that population decline is not imminent, inevitable or necessarily catastrophic.

The population collapse narrative hinges on three key misunderstandings. First, it misrepresents what standard fertility measures tell us about childbearing and makes unrealistic assumptions that fertility rates will follow predictable patterns far into the future. Second, it overstates the impact of low birth rates on future population growth and size. Third, it ignores the role of economic policies and labor market shifts in assessing the impacts of low birth rates.

Fertility fluctuations

Demographers generally gauge births in a population with a measure called the total fertility rate. The total fertility rate for a given year is an estimate of the average number of children that women would have in their lifetime if they experienced current birth rates throughout their childbearing years.

Fertility rates are not fixed — in fact, they have changed considerably over the past century. In the U.S., the total fertility rate rose from about 2 births per woman in the 1930s to a high of 3.7 births per woman around 1960. The rate then dipped below 2 births per woman in the late 1970s and 1980s before returning to 2 births in the 1990s and early 2000s.

Since the Great Recession that lasted from late 2007 until mid-2009, the U.S. total fertility rate has declined almost every year, with the exception of very small post-COVID-19 pandemic increases in 2021 and 2022. In 2024, it hit a record low, falling to 1.6. This drop is primarily driven by declines in births to people in their teens and early 20s — births that are often unintended.

But while the total fertility rate offers a snapshot of the fertility landscape, it is not a perfect indicator of how many children a woman will eventually have if fertility patterns are in flux — for example, if people are delaying having children.

Picture a 20-year-old woman today, in 2025. The total fertility rate assumes she will have the same birth rate as today's 40-year-olds when she reaches 40. That's not likely to be the case, because birth rates 20 years from now for 40-year-olds will almost certainly be higher than they are today, as more births occur at older ages and more people are able to overcome infertility through medically assisted reproduction.

A more nuanced picture of childbearing

These problems with the total fertility rate are why demographers also measure how many total births women have had by the end of their reproductive years. In contrast to the total fertility rate, the average number of children ever born to women ages 40 to 44 has remained fairly stable over time, hovering around two.

Americans continue to express favorable views toward childbearing. Ideal family size remains at two or more children, and 9 in 10 adults either have, or would like to have, children. However, many Americans are unable to reach their childbearing goals. This seems to be related to the high cost of raising children and growing uncertainty about the future.

In other words, it doesn't seem to be the case that birth rates are low because people are uninterested in having children; rather, it's because they don't feel it's feasible for them to become parents or to have as many children as they would like.

The challenge of predicting future population size

Standard demographic projections do not support the idea that population size is set to shrink dramatically.

One billion people lived on Earth 250 years ago. Today there are over 8 billion, and by 2100 the United Nations predicts there will be over 10 billion. That's 2 billion more, not fewer, people in the foreseeable future. Admittedly, that projection is plus or minus 4 billion. But this range highlights another key point: Population projections get more uncertain the further into the future they extend.

Predicting the population level five years from now is far more reliable than 50 years from now — and beyond 100 years, forget about it. Most population scientists avoid making such long-term projections, for the simple reason that they are usually wrong. That's because fertility and mortality rates change over time in unpredictable ways.

The U.S. population size is also not declining. Currently, despite fertility below the replacement level of 2.1 children per woman, there are still more births than deaths. The U.S. population is expected to grow by 22.6 million by 2050 and by 27.5 million by 2100, with immigration playing an important role.

Will low fertility cause an economic crisis?

A common rationale for concern about low fertility is that it leads to a host of economic and labor market problems. Specifically, pronatalists argue that there will be too few workers to sustain the economy and too many older people for those workers to support. However, that is not necessarily true — and even if it were, increasing birth rates wouldn't fix the problem.

As fertility rates fall, the age structure of the population shifts. But a higher proportion of older adults does not necessarily mean the proportion of workers to nonworkers falls.

For one thing, the proportion of children under age 18 in the population also declines, so the number of working-age adults — usually defined as ages 18 to 64 — often changes relatively little. And as older adults stay healthier and more active, a growing number of them are contributing to the economy. Labor force participation among Americans ages 65 to 74 increased from 21.4% in 2003 to 26.9% in 2023 — and is expected to increase to 30.4% by 2033. Modest changes in the average age of retirement or in how Social Security is funded would further reduce strains on support programs for older adults.

What's more, pronatalists' core argument that a higher birth rate would increase the size of the labor force overlooks some short-term consequences. More babies means more dependents, at least until those children become old enough to enter the labor force. Children not only require expensive services such as education, but also reduce labor force participation, particularly for women. As fertility rates have fallen, women's labor force participation rates have risen dramatically — from 34% in 1950 to 58% in 2024. Pronatalist policies that discourage women's employment are at odds with concerns about a diminishing number of workers.

Research shows that economic policies and labor market conditions, not demographic age structures, play the most important role in determining economic growth in advanced economies. And with rapidly changing technologies like automation and artificial intelligence, it is unclear what demand there will be for workers in the future. Moreover, immigration is a powerful — and immediate — tool for addressing labor market needs and concerns over the proportion of workers.

Overall, there's no evidence for Elon Musk's assertion that "humanity is dying." While the changes in population structure that accompany low birth rates are real, in our view the impact of these changes has been dramatically overstated. Strong investments in education and sensible economic policies can help countries successfully adapt to a new demographic reality.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Even brief exposure to air pollution may alter the structure of the placenta and push the organ into an inflammatory state, recent laboratory research finds.

Scientists already knew that particles found in air pollution can reach the placenta and get taken up by immune cells there.

"There's no doubt that particles are entering the bloodstream and then accumulating, or getting to, the placenta and being taken up by placental cells," said Dr. Jonathan Grigg, a professor of pediatric respiratory and environmental medicine at Queen Mary University of London who was not involved in the recent study.

The new work added to this understanding by zooming in on special immune cells of the placenta — called Hofbauer cells — to see how their function changed after they were exposed to compounds found in real air pollution.

"I think that this is an important step in filling in the gap between what we know from epidemiological studies," Grigg said.

Those studies pointed to links between exposure to pollutants during pregnancy and the risk of the blood-pressure disorder preeclampsia, for instance. Preeclampsia is tied to poor blood flow to the placenta, and thus low oxygen in the organ. Some researchers argue that placental dysfunction is the root of preeclampsia, but not everyone agrees, as some point instead to the maternal cardiovascular system. But nonetheless, the placenta is thought to be a key factor in the disease.

The recent research, published online in March in the Journal of Environmental Sciences, will also run in the journal's February 2026 print issue. It used what's known as "ex vivo dual placental perfusion," which means the scientists collected full-term placentas from volunteers who donated them at the time of birth, either via cesarean section or vaginal delivery. In all, 13 healthy placentas were donated.

Related: Lab-grown mini-placentas reveal clue to why pregnancy complications happen

"You can't really expose women to air pollution as an experiment," study co-author Dr. Stefan Hansson, a professor of obstetrics and gynecology and a senior consultant in obstetrics at Lund University in Sweden, told Live Science. "So the best model, then, is the placenta perfusion system that we used."

After birth, the placentas are connected to an artificial perfusion system that mimics elements of the female reproductive system. "Within 30 minutes, you hook it up in an artificial womb and uterus," Hansson explained. Tubes connected to one side of the placenta represent the maternal circulatory system, while tubes on the other stand in for the umbilical cord that would connect to the fetus.

Tubes feed nutrients and oxygen to the placentas, keeping them healthy for about six hours and mimicking both the maternal and fetal sides of the organ. Meanwhile, scientists can monitor the organ's metabolism, homeostasis, blood-pressure levels and the behavior of its immune cells.

"That's a good thing in the sense it's covering perhaps the more complex interactions between cells, how fluid and particles are moving through cells," Grigg said. By comparison, studying individual placental cells in a lab dish is arguably less realistic.

The researchers then introduced air pollutants into the system to see what happened. Six placentas were left unexposed to pollution, to serve as a comparison; five were exposed to pollution for five hours; one was exposed for 60 minutes; and one was exposed for 30 minutes. Tissues and fluids were sampled from the system before, during and after these perfusions.

The pollutants themselves were drawn from a previous sampling of air pollution in Malmö, Sweden taken in spring 2017. The samples were collected at a street crossing that sees an annual average traffic density of about 28,000 vehicles. The team focused on "fine" particulate matter, or PM2.5, which includes particles smaller than 2.5 micrometers.

On that point, Grigg told Live Science that "the concentrations of particles that they're using in the perfusates are almost certainly very much higher than the very small concentrations that are going around the body," based on previous research. So there's a question about whether the doses they've tested closely reflect real life. "I think that's probably a valid limitation for this," he said.

Related: Canada's 2023 wildfires contributed to 87,000 early deaths worldwide, study estimates

Nonetheless, at the concentrations tested, the pollutants had a clear effect on the placentas. Even when exposed for only 30 minutes, the placentas showed distinct changes in their collagen, a structural protein that helps organize the tissue. The collagen appeared looser and "disrupted" compared with the dense, organized collagen of the unexposed tissues.

The team also noted that, after an hour of exposure, the placentas started making more human chorionic gonadotropin (hCG), a hormone that peaks in the first trimester and helps maintain the uterine lining. However, high levels of the hormone in the second trimester have been tied to a higher risk of preeclampsia, studies suggest. The new study hints that air pollution may be a factor that drives up hCG levels, though that idea needs to be confirmed.

Meanwhile, the Hofbauer cells of the exposed placentas had a "visible activated appearance" and had shifted into an inflammatory state. In a healthy placenta, the cells are typically biased toward an anti-inflammatory state, but in the context of preeclampsia, they tend to shift in the other direction, the researchers noted in their report.

"This is, of course, an artificial setup and you're exposed for a couple of hours," Hansson noted. You can extrapolate and assume that, in a full-term pregnancy, these harmful effects might accumulate, he said. But as it stands, the placental perfusion system can't directly capture the effects of such long-term exposure, and it also looks only at full-term placentas, not at those in earlier stages of development.

It stands to reason, though, that "if it's happening all the time, then that's going to be clinically relevant," Grigg said.

The results hint that if the inflammation driven by the Hofbauer cells could be subdued with a drug, that may help ward off one factor contributing to preeclampsia in polluted areas, Hansson suggested. That idea remains to be tested in trials, though, and inflammation isn't the only feature of preeclampsia.

What's more, a more effective intervention would be to reduce particulate matter in the air, Grigg said. "We should be reducing exposure to PM2.5; you don't need any more information about that [to justify taking action]," he said.

Grigg also cautioned that the new results don't necessarily point to precautions that individual pregnant people should take.

"I sort of hesitate to say, 'Well, pregnant women have to do something different to protect themselves,'" he said. "There are enough things that pregnant women have to do rather than thinking about how they move around the city."

This article is for informational purposes only and is not meant to offer medical advice.

The widely used acne medicine Accutane could be used to treat male infertility, a small study hints.

For men with infertility caused by extremely low sperm counts or a complete lack of sperm, the only medical option is to undergo surgery to collect sperm directly from the testicles to then use for in vitro fertilization (IVF). But this is a significant surgery that involves discomfort; potential risks, such as infection; and a prolonged recovery period. Moreover, the surgery only yields sperm about half the time.

Now, researchers are exploring an alternative: isotretinoin, better known as Accutane, a drug that has been used for decades to treat severe acne. In a small study published in July in the Journal of Assisted Reproduction and Genetics, the drug stimulated sperm production in some men who at baseline had no or very few sperm in their ejaculate.

"The idea that a well-studied drug could stimulate spermatogenesis [sperm production] in men with severely impaired sperm production is exciting because it opens the door to a non-surgical option for men who might otherwise require invasive testicular sperm retrieval," Dr. Justin Houman, an assistant professor of urology at Cedars-Sinai Medical Center who was not involved in the study, told Live Science in an email.

"That said, the study is small, preliminary, and requires replication in larger, randomized trials before we can consider it a true breakthrough," said Houman, who is also the chief clinical officer at Bastion Health.

Dr. Brian Levine, the founding partner and practice director of CCRM Fertility of New York, who was not involved in the study, also expressed cautious optimism about the findings.

"The prospect of helping a patient avoid the pain, recovery time, and emotional stress of surgery is a source of genuine excitement for me and my colleagues," he told Live Science in an email. But "this is not a cure-all, and there is much more research to be done," he said.

Related: Man gets sperm-making stem cell transplant in first-of-its-kind procedure

So, how might a skin medication help men make sperm?

Previous studies have found that infertile men often have lower levels of retinoic acid inside their testes. This molecule, a derivative of vitamin A, is essential for the normal development of sperm cells. It controls the development of immature germ cells into mature sperm cells and facilitates the release of mature sperm into the seminiferous tubules within the testes. This link led scientists to test isotretinoin — a compound that mimics natural retinoic acid — as a potential way to jump-start sperm production.

For this study, researchers enrolled 26 men with nonobstructive azoospermia — a condition in which there is no sperm in the ejaculate due to a problem with sperm production — and four men with cryptozoospermia, in which extremely low numbers of sperm are present in the ejaculate.

All of the participants took 20 milligrams of isotretinoin twice daily for at least six months. Their blood values, hormone levels and semen were closely monitored at several time points during the study.

Of the 30 men in the study, 11 began producing motile sperm — sperm that swim efficiently — in their ejaculate. This enabled these men and their partners to start IVF without the need for surgical sperm collection. This treatment-responsive group included all four men with cryptozoospermia and seven men who had previously shown no sperm at all in their ejaculate.

For the remaining men who still lacked sperm in their ejaculate after treatment, doctors had to use surgery to collect sperm for IVF. But after isotretinoin, the procedure took far less time — 63 minutes, on average, compared with 105 minutes before treatment. (The report didn't note exactly why the surgery was more efficient after Accutane.)

At the time the study was published, nine IVF cycles had been carried out with sperm collected after isotretinoin treatment, leading to multiple healthy embryos, some ongoing pregnancies and one live birth so far, the researchers reported.

The treatment wasn't free of side effects, however. All 30 men developed dry skin and chapped lips, and about half reported feeling irritable after the treatment. Some also had rashes and elevations in their cholesterol and triglyceride levels. Because isotretinoin can these levels and liver function, patients would need regular blood tests during treatment, Houman said. When people take Accutane for acne, doctors recommend periodic blood tests, although they don't agree on how frequently these tests should be done.

"Importantly, we do not yet know the optimal dose, duration, or long-term safety of isotretinoin in men seeking fertility," he said. "Another drawback is that response rates are unknown, and many men may not benefit at all."

Until data from larger studies is available, isotretinoin shouldn't be used to treat male infertility outside of clinical trials, Houman cautioned.

For women, isotretinoin can be taken safely outside of pregnancy, but during pregnancy, it's considered highly dangerous because it can cause severe birth defects. This risk is so significant that the drug carries a black box warning and strict contraception requirements to adhere to when taking the medication.

"In men, the situation is different," Houman said. The drug doesn't appear to damage sperm DNA or pose risks to reproductive partners or the resulting children. "In fact, this new research suggests it may have a paradoxical benefit by enhancing sperm production in certain men." This highlights "the very different biological contexts" between the male and female reproductive systems, he said.

Looking ahead, the researchers hope to figure out which male infertility patients are most likely to benefit from isotretinoin; how to fine-tune the timing and dosage of the treatment; and whether the drug can improve sperm quality and fertility outcomes.

The possibility that a simple course of oral medication could restore sperm production for some men "would represent a monumental shift in how we approach male infertility", Levine said. "It offers a new layer of hope — not just the hope of finding sperm, but the hope of restoring a natural biological function."

This article is for informational purposes only and is not meant to offer medical advice.

Researchers have created magnetically-controlled "sperm bots" that they can pilot around and monitor in real time.

These tiny microrobots are bull sperm cells coated in magnetic nanoparticles. Researchers haven't tested them inside a real organism, whether cow or human, yet, but they demonstrated that they can control the sperm bots inside a life-sized anatomical model of the female human reproductive system and track their progress with X-rays.

The sperm bots, described Tuesday (Sep. 2) in the journal npj Robotics, could one day be used to improve reproductive medicine, drug delivery and infertility diagnosis, the researchers said in a statement.

"We're turning nature's own cell delivery systems into programmable microrobots," study lead author Islam Khalil, an associate professor in the robotics and mechatronics research group at the University of Twente in the Netherlands, said in the statement.

Related: 'I would never let a robot incubate my child': Poll on 'pregnancy robots' divides Live Science readers

Microbots are microscopic devices that scientists are developing so that they can be deployed inside the body for highly precise, targeted medical treatments. For example, in 2022, researchers used an army of swimming microbots to eradicate a deadly pneumonia infection in mice.

When it comes to reproductive health, scientists say that microbots have the potential to deliver drugs directly to the uterus, fallopian tubes and other difficult-to-access parts of the female reproductive system. Such a targeted drug delivery system could improve treatments for ailments such as uterine cancer and fibroids, the study authors propose.

Khalil was part of a team that unveiled biohybrid magnetic sperm microrobots in 2020. In the new study, researchers found that increasing the concentration of iron oxide nanoparticles on the bots' outer coating improved the team's ability to control and detect the little machines, while still ensuring the nanoparticles weren't harmful to the uterus. At least, the bots weren't toxic to human uterine cells after 72 hours of exposure.

The team tested their little sperm bots in a 3D printed model of a portion of the female reproductive tract, using an external magnetic field to pilot them from the ersatz cervix, through the uterine cavity, and toward the fallopian tubes, where fertilization most often occurs. They found that the bots could be tracked throughout the journey in real time using X-rays, something that isn't possible with natural sperm.

"Until now, visualising sperm inside the body was nearly impossible," Khalil said.

A lack of real-time sperm tracking has hampered scientists' understanding of reproductive health and fertility treatments, the authors say. The researchers noted that having a noninvasive way of tracking sperm could help them better understand sperm transport systems and male infertility, for instance.

Scientists are one step closer to understanding how human ovaries develop their lifetime supply of egg cells, known as ovarian reserve.

The new research, published Aug. 26 in the journal Nature Communications, mapped the emergence and progression of the cells and molecules that develop into the ovarian reserve in monkeys, from the early stages of ovarian development in an embryo to six months after birth.

This map fills in some of the blanks in "really important areas of just unknown biology," study co-author Amander Clark, a developmental biologist at UCLA, told Live Science.

Researchers can now use this map to build better models of the ovary in the lab to study reproductive diseases related to the ovarian reserve, she said, such as polycystic ovary syndrome (PCOS) — a complex hormonal disorder that can result in infertility.

Mysterious development

Ovaries are the primary female reproductive organs and play two essential roles in female health and reproduction: making egg cells; and making sex hormones, including estrogen, progesterone and testosterone.

Ovaries first begin to develop in embryos around six weeks after fertilization. In the early stages, germ cells — which develop into egg cells — divide and connect to one another in complex chains called nests. When these nests burst open, individual egg cells are released and are encased by a layer of specialized cells called pregranulosa cells, which support the young eggs and signal when it's time to mature.

These eggs encircled by pregranulosa cells are called primordial follicles, and are what make up the ovarian reserve.

Primordial follicles start to form around 20 weeks after fertilization, and cluster on the inside edges of the ovaries. When the follicles closest to the center of the ovary in these clusters mature, they grow and produce sex hormones.

So it is the primordial follicles that ensure the ovaries perform their jobs of producing mature eggs and releasing hormones, Clark said.

Multiple ovarian diseases and conditions are rooted in problems with the cells in the ovarian reserve. For example, although the exact cause of PCOS is still unknown, it involves dysfunction in the primordial follicles. And yet, very little work has been done to understand their development.

Building a map of how and when the ovarian reserve forms during pregnancy can help figure out why certain diseases and issues with fertility crop up later in life. "That's where this study came in," Clark said.

Related: 1st 'atlas' of human ovaries could lead to fertility breakthrough, scientists say

Surprise findings

To investigate how ovarian reserves originate in primates, Clark and her team looked at a monkey species that is physiologically similar to humans. This makes it a good stand-in for what happens developmentally in humans, she said.

First, female monkey embryos and fetuses were harvested at various developmental stages and ovarian tissue samples were taken. The researchers focused on several key time points: day 34 (when the sex organs become either male or female), 41 (early ovarian growth), 50-52 (end of embryonic period), 100 (when the egg nest expands) and 130 (when the nest bursts and the primordial follicles form) after fertilization.

Then, the team analyzed the position and molecular fingerprint of the ovarian cells to understand the critical events in the formation of the ovarian reserve.

They found that pregranulosa cells formed in two waves, but it was only during the second wave, between days 41 and 52, that pregranulosa cells formed that would go on to swarm the young eggs to form primordial follicles.

They also identified two genes that seem to be active prior to this second wave. The researchers said that looking further into the function of these genes may help to pinpoint the developmental origins of ovarian reserve problems.

Also, Clark said the team was completely surprised to find that "before birth, the ovary goes through practice rounds of folliculogenesis," meaning that very soon after the ovarian reserve is made, some of the more centrally located follicles mature and can produce hormones. The researchers suggest that determining why these follicles normally activate could provide insight into the causes of PCOS.

"This study adds fresh and highly relevant new insight," Luz Garcia-Alonso, a computational biologist at the Wellcome Sanger Institute who was not involved in the study, told Live Science in an email. The work in primates complements earlier work on the formation of the ovarian reserve and supports our understanding of how primordial follicles form in humans, she added.

Still, the researchers are looking at a highly dynamic period in development, when the cellular makeup of an embryo can change dramatically, Garcia-Alonso said. And they have big time gaps between their observation periods.

"This stage when cell lineages are specified is very dynamic, and cell composition changes within days," Garcia-Alonso said. So the team should collect more fine-scale data on more time points to get a better picture of what is going on, she added.

Editor's Note: This story was updated on Tuesday, Sept. 23 at 9:20 a.m. EDT to add additional comment from Garcia-Alonso.

This article is for informational purposes only and is not meant to offer medical advice.

Would you use a surrogate robot to carry your child from conception to birth? In a Live Science poll, we asked readers if they would use a so-called "pregnancy robot" in response to false news of the technology being developed in China that spread across the web.

The supposed CEO of the robot company reportedly proclaimed that the development of the robot was close to completion, and that a prototype would be ready as early as 2026. While the story was pure fiction, it sparked a discussion about whether such technology is feasible — or ethical.

Around 180 readers responded to our poll, which was published on Aug. 23. As of today (Aug. 29), results show 30% of responders would use a pregnancy robot as long as they were sure their baby was healthy and not harmed by the process, while 29% of responders selected no, with the opinion that the process is completely unethical.

11% of respondents said they would use a surrogate robot with no questions asked, while 8% expressed doubts that the technology would keep a baby safe during development.

"I would never let a robot incubate my child. I just don’t think a robot could ever give a baby everything it needs to develop properly," Rene wrote. "There’s something about that natural bond between a mother and her baby — maybe even a brain-to-brain connection — that feels too important to replace."

For some their decision was based around ethical views. "This is just more anti human science that will only further our fall as a civilization," Thatguy wrote, describing the technology as "disgusting" and "repulsive."

On the other side, ShanMorgain suggested it could help mitigate some of the risks associated with pregnancy. "Omigod YES. Pregnancy and birth are atrocious and escaping their blight — which can mean lifelong damage — would be wonderful. Some would choose the natural method fine for them. I loved the idea when I met it in Lois McMaster Bujold's 'Vorkosigan' series. Her imagined incubator is mobile and can stay close to the parents. Big impact on gender equality."

A viral story spread through the tabloids this week, proclaiming that a CEO of a technology company in China was in the midst of developing a "pregnancy robot." A prototype of the bot would be ready by next year, the CEO projected, and would be designed to sustain a human pregnancy from conception to birth, around 10 months.

The robot and the related story were — as you might have guessed — pure fiction. But the viral tale nonetheless raised questions about whether designing such a robot could be possible with today's technology, and what ethical quandaries that possibility might raise, in turn.

If a "pregnancy robot" existed, would you consider using one? Take our poll below, and let us know what you think of this sci-fi-sounding idea in the comments below. If you chose "maybe," what would sway your decision?

Related: 'Pregnancy robot from China' is fake, but is the technology behind it possible?

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Bizarre imagery flooded newsfeeds this week as word spread about a new "pregnancy robot" in development in China. The images featured plump human babies curled inside the bellies of chrome-plated robots complete with visible wiring and ample curves, despite their lack of mammary glands.

Many outlets — including Newsweek, The Economic Times, and ChosunBiz — named a Chinese outlet, Kuai Ke Zhi, as the story's source. Zhang Qifeng, the developer of the bot intended to carry a pregnancy from conception to birth, reportedly told the outlet that a prototype would be ready as early as 2026 at a price point under 100,000 yuan (around $13,900 USD).

"Some people don't want to get married but still want a 'wife'; some don't want to be pregnant but still want a child," Zhang said, according to Newsweek. "Mature" artificial womb technology just "needs to be implanted in the robot's abdomen so that a real person and the robot can interact to achieve pregnancy," he said, according to ChosunBiz. The nature of that human-robot interaction was not detailed.

Depending on the article, Zhang was cited as the CEO or founder of Kaiwa Technology, a Guangzhou-based company, or as a PhD affiliated with Singapore's Nanyang Technological University (NTU). Finding no online evidence of Kaiwa Technology, Live Science contacted NTU about their purported affiliation with Zhang Qifeng.

"We would like to inform you that no one by the name of 'Zhang Qifeng' graduated from NTU with a PhD," an NTU spokesperson told Live Science via email. "Our checks also showed no such 'gestation robot' research has been conducted at NTU."

As you may have suspected — and as Snopes has also confirmed — the pregnancy robot isn't real. But the viral story raised questions about the potential of artificial-womb technology. Would it be possible to build a pregnancy robot? Or is the concept pure science fiction? Live Science spoke with experts about the idea, discussing whether it would technically be possible and whether anyone should even try.

"Should we do it? My answer would be categorically 'no,'" said Dr. Harvey Kliman, director of the Reproductive and Placental Research Unit at Yale University School of Medicine. "That being said, intellectually, I think it's interesting to think about the challenges because it helps us actually reflect about what is the beauty and miracle of a normal pregnancy."

Related: If 'pregnancy robots' were real, would you use one?

Artificial wombs?

The pregnancy robot is fake, but scientists have been developing artificial wombs. At Children's Hospital of Philadelphia (CHOP), scientists are developing a womb-like device called the "extra-uterine environment for newborn development," or EXTEND. The eventual hope is to support babies who are born extremely premature, between 23 and 28 weeks of gestation.

Recent advances have decreased the death rate associated with preterm birth, but health issues, including chronic lung disease and neurodevelopmental problems, remain a big concern for babies born that early. To decrease these risks, CHOP researchers aim to create a uterus-like environment that babies can be placed in after delivery to help them over the 28-week mark.

The device includes a bag full of amniotic fluid, which is made in the lab and contains key nutrients and growth factors. The umbilical cord is attached to an "external oxygenator" that partly stands in for the placenta, facilitating an exchange of oxygen and carbon dioxide. Within the device, a baby would be insulated from changes in temperature, pressure and light, as well as from exposure to germs.

EXTEND has so far been tested with lambs. In a 2017 paper, the team showed that fetal lambs could be supported in the device for a month and that their development continued much as it would have in the womb. In a 2024 paper, they collaborated with Duke University researchers to see how EXTEND impacted gene activity in the brain. The device helped preserve gene activity in premature lambs' brains so that it resembled that of lambs that remained in the womb for much longer.

Meanwhile, some researchers are working on artificial placentas that would fulfill the same purpose as EXTEND, supporting premature babies. These devices have also been tested in lambs but are farther out from human trials than EXTEND is.

The EXTEND team aims to move into human trials soon, though there are questions about when and how it would be ethical to test the device, given many premature babies have a fighting chance with existing technologies.

"In a human setting, a couple weeks is not enough," said Dr. Lusine Aghajanova, a fertility specialist and clinical associate professor of obstetrics and gynecology at Stanford Medicine, in reference to the length of the tests done so far in lambs. "What that study showed is that it's a concept that can be possible, but it's more complicated than we think," she told Live Science.

Throughout their efforts, the EXTEND developers have stressed that the device is intended as a bridge for premature babies moving from the womb into the world; it is not intended to be used to push fetal viability earlier than 23 weeks. Of course, there's a big difference between keeping an ailing baby alive and gestating a baby from conception, as the fake Kaiwa pregnancy robot was supposed to do.

Related: Should we rethink our legal definition of a human embryo?

Like a 'tomato plant suspended in water'

Presumably, a gestation robot might need to deal with a particularly tricky part of pregnancy: implantation.

In an unassisted pregnancy, an egg travels through a fallopian tube, where it is typically fertilized before moving into the uterus and implanting in the uterine wall. In fertility treatments, such as in vitro fertilization (IVF), a fertilized egg is placed into the uterus, where ideally, it then implants itself. That aspect of the treatment is not directly orchestrated by doctors.

In a robotic incubator, though, implantation may not be a critical step, Kliman said. "I'm thinking about hydroponics," he said. "Think of it as a tomato plant suspended in this bucket of water, right?"

Similar to the EXTEND studies with lambs, in theory, a human embryo could be suspended in fluid rather than embedded in something akin to the uterine wall, he said. The real challenge would be ensuring that the embryo remains suspended, so it can grow unimpeded, and that it's supplied with adequate nutrients and factors to grow. The placenta "doesn't actually have to attach to anything or burrow into anything" in that kind of setup, Kliman said.

Aghajanova, on the other hand, thinks recreating implantation would be key. "Implantation is absolutely important," she said. "It's the seed and the soil," referencing the embryo and the uterine lining. Abnormalities in the uterine lining can undermine both fetal growth and placental development, she argued, so some stand-in for the tissue would likely be necessary in a pregnancy robot.

Even if the implantation issue was addressed, delivering the right nutrients to the fetus at the right time could still be tricky.

Early in pregnancy — roughly up to the eighth week or so — glands in the uterine lining produce a nutritious "milk" for the developing embryo and placenta. At that point, blood flow from mother to womb is not fully established, in part, because the maternal blood is too oxygenated, Kliman said. "That high-oxygen state causes too many free radicals and would destroy the DNA of the dividing embryo," he said, so instead, the early womb maintains a low-oxygen state.

In a robot pregnancy, you'd need to carefully recreate that transition from low- to high-oxygen, as well as maintain the womb-like environment and keep it flush with nutrients for months on end. Maternal metabolism shifts dramatically in pregnancy, Aghajanova said, so it would be difficult to know what dose of oxygen is needed at any given stage of development.

"That's mind boggling to me. I'm just trying to think of any system that would work flawlessly for nine months and not get infected," meaning exposed to germs that could derail the whole process, Kliman said. "We're talking extreme challenges of just the machinery, the reliability, the nutrients, the getting rid of the waste — and again, I think the biggest problem, to be honest with you, would be infection."

While those aspects of an artificial womb would be complex, it might be simpler than human reproduction in other respects, Kliman mused. In human pregnancy, the embryo and placenta must be protected from the maternal immune system, lest they be targeted as foreign invaders. Additionally the uterus undergoes changes to create a suitable environment for the embryo, and the placenta releases hormones that prep the mammary glands to make milk. These factors would be irrelevant in a machine, he said.

There are questions about how the fetal immune system might develop differently in a robot. In a human pregnancy, antibodies pass from maternal blood to the fetus via the umbilical cord. That's why a variety of vaccines are given in late pregnancy: The vaccines stimulate maternal antibody production, those antibodies pass to the fetus, and newborns enter the world with some protection against dangerous infections. And additional, non-vaccine-induced antibodies also cross over.

Given robots lack immune systems, developers of a pregnancy robot might need to figure out how to replicate this process, perhaps with lab-made antibodies or with donated blood.

"I don't think that would be that hard," Kliman said. Some of those antibodies could be supplied after birth via breastmilk or through formula containing lab-made antibodies, he suggested. And you might take extra precautions to keep the baby from being exposed to too many germs too soon, if you knew that might be an issue, he added.

In the womb, the maternal immune system must avoid attacking the growing fetus while also protecting it from pathogens, Aghajanova said. The former issue might not be relevant in a robotic pregnancy, but that latter protection would still be necessary, she said.

Related: 'We know what to do; we just have to implement it.': Pregnancy is deadlier in the US than in other wealthy countries. But we could fix that.

Unanswered questions

An additional factor to consider might be the vaginal microbiome, which contains bacteria, fungi and other microorganisms that studies suggest impact the health of the developing fetus. Figuring out how and what to deliver into the robot to mimic this complex microbial community could be tricky, as we don't fully understand which species are helpful to fetal development.

With the loss of a microbiome would likely come the addition of plastic components within the robot itself, Aghajanova added. It's unclear how all that plastic could sway early development, but it likely wouldn't be great, she suggested.

Other quandaries cloud the notion of a pregnancy robot: How would the eggs and sperm be sourced? Whose gametes would be used to test and optimize the device, proving it could lead to a live birth? Where could such research be conducted, legally? Would fertilization occur inside the bot itself, or via a lab procedure akin to IVF? Who is tasked with maintaining and monitoring the bot's functions throughout the "pregnancy"? What would the birthing process look like for a robot, and would engineers be needed in the delivery room? Are there yet-unknown aspects of human pregnancy that a baby grown in a machine would miss out on?

In our current reality, many of these questions remain unanswerable — but they would certainly make a compelling premise for a sci-fi novel.

"It's good science fiction, but in a word, it doesn't exist yet," Aghajanova said. And "we are not that desperate [for such technology], especially in the U.S." In the United States, patients have access to fertility treatments, donor eggs and surrogates, she said.

For Kliman's part, he said that his main takeaway from this thought experiment is simply "what a miracle a pregnancy is."

"We're just little feeble beings trying to conceive of some way to do this artificially, and look at what nature has done," he said. "And it happens four million times a year in our country; we get a normal delivery. So that's the miracle."

This article is for informational purposes only and is not meant to offer medical advice.

Jordyn Albright's pregnancy-and-delivery journey was difficult from the start. Her pregnancy was high risk, due to both in vitro fertilization (IVF) and high blood pressure during pregnancy. She was induced three weeks early and went through 60 hours of labor before delivering.

With her son in her arms, the worst should have been behind her. But within moments, her doctor realized her placenta was stuck to her uterine wall. Hospital staff gathered around her, trying to remove the placenta manually — "a horribly painful experience," Albright, 32, said. She wouldn't stop bleeding.

Mere minutes after giving birth, Albright passed out from blood loss. What she didn't hear was her care team calling for a rapid response, which is an alert in labor-and-delivery units that brings an emergency team of doctors and nurses rushing to the room. This team saved Albright's life with 4 pints of blood (she would later need 2 more) and whisked her to emergency surgery to remove the retained placenta.

This harrowing experience was followed by a traumatic few days in the intensive care unit (ICU) and separation from her newborn. It was compounded by weeks in the neonatal ICU for the new baby, who contracted a rare bacterial infection after birth. But Albright and her husband, Jeffrey Albright, credit their care team with saving both mom and child.

"This could have been so much worse," Jeffrey Albright, 32, told Live Science. "In any way you can think of it, it could have been worse."

For too many families, it is worse. A higher percentage of people die in pregnancy, childbirth or the postpartum period in the U.S. than in comparable wealthy countries. It's a problem of health disparities, access to health care, and how individual hospitals handle emergencies — and the problems could deepen with recent policy decisions in the U.S., experts say.

Despite the bleak numbers, there is hope. Evidence suggests that most of these deaths are preventable and that some relatively straightforward interventions could slash the maternal death rate. Those measures include better prenatal monitoring to prevent emergencies in the first place, as well as more training for hospital personnel to react when emergencies do happen.

"We know what to do," said Jeanne Conry, past president of the American College of Obstetricians and Gynecologists (ACOG) and the International Federation of Gynecology and Obstetrics. "We just have to implement it."

Causes of maternal death

The Centers for Disease Control and Prevention (CDC) defines maternal mortality as the death of a patient during pregnancy or up to 42 days after delivery from any cause related to or aggravated by the pregnancy or pregnancy care. For example, someone who dies in a car wreck during pregnancy wouldn't be counted, but someone with a preexisting heart condition whose condition worsened due to pregnancy would be.

Although maternal death is rare in the U.S., the rate is higher than in other wealthy nations. Provisional CDC data suggest that in 2024, there were 19 maternal deaths for every 100,000 live births, compared with 8.4 per 100,000 in Canada, 8.8 per 100,000 in South Korea, 5.5 per 100,000 in the U.K. and zero in Norway, according to The Commonwealth Fund, a health policy foundation.

The U.S. has long been an outlier among its wealthy peers in maternal mortality, even though the country spends about twice as much per person on health care as other large, wealthy nations do, according to the Peterson Center on Healthcare and the health policy organization KFF, a health policy research organization.

"We rank very poorly on the world stage," said Dr. Monique Rainford, an assistant professor of obstetrics, gynecology and reproductive sciences at the Yale School of Medicine and the CEO and co-founder of Enrich Health, a startup that aims to provide evidence-based prenatal care.

According to The Commonwealth Fund, about half of U.S. maternal deaths happen the day after birth, and about a third occur during pregnancy. During pregnancy, one-third of the deaths are due to stroke and heart conditions, according to the March of Dimes, while emergencies such as hemorrhage cause the most deaths during labor and delivery. Bleeding, high blood pressure (including pregnancy-induced conditions such as preeclampsia, a life-threatening persistent rise in blood pressure that can develop during pregnancy or up to six weeks postpartum), infection and cardiomyopathy (a weakening of the heart muscle) cause the most deaths after delivery.

"What's coming out of our research is that cardiovascular disease is really increasing," Conry told Live Science.

While the U.S. has high rates of certain conditions that increase the risk of complications during pregnancy, birth and the postpartum period — such as obesity — other countries with high rates of these risk factors have much lower rates of death than the U.S.

Maternity deserts

One factor in the U.S.' comparatively poor outcomes is that many women live in "maternity deserts" — areas where there is no nearby hospital that offers maternity services or neonatal specialists. Thirty-five percent of counties in the United States are maternity care deserts, according to the March of Dimes.

As of 2022, 52% of rural hospitals did not offer obstetric care, and the problem has worsened since then. According to 2024 research in the journal JAMA, 238 rural hospitals stopped offering obstetrics between 2010 and 2022, and only 26 rural hospitals added obstetrics to their offerings in that time period. (During the same period, 299 urban hospitals lost obstetrics, but 112 added in new offerings.)

In addition, a 2021 study of New Jersey maternity hospital closures found that women had a higher rate of maternal morbidity rate — a measure of serious and life-threatening complications around pregnancy and childbirth — if they gave birth after an obstetrical unit closed in a nearby hospital.

Lack of maternity care is a big problem in rural areas, but it's not exclusively a rural one. Around 35% of urban hospitals lack obstetric care. In addition, other health care access problems can make it difficult for women to get to prenatal appointments where problems can be spotted and managed early on.

Even in dense Chicago, "if your Medicaid provider is not in network, you're a lot of times forced to use public transport in horrible weather, often with other children, to get preventative care," said Star August Ali, a certified professional midwife and the executive director and founder of the Black Midwifery Collective in Chicago, which aims to train and support Black midwives.

Looming cuts

The Medicaid cuts in the "Big Beautiful Bill Act" signed into law in July could spell deep trouble for maternal mortality. The cuts are expected to hit rural hospitals hard, according to KFF, with the likely closure of 144 rural labor and delivery wards.

And about 41% of U.S. births are covered through Medicaid. While it's not clear how the cuts will affect enrollment during pregnancy, without that coverage, people may not have access to treatments and monitoring that could head off some life-threatening emergencies.

The impact of these policies is not equal. Medicaid covers about 28% of births to white mothers, 64% of births to Black mothers, and 67% of births to American Indian or Alaska Native moms. Younger women are also more likely to be covered by Medicaid than by private insurance, with almost 79% of births to moms under age 20 being covered by the government program.

If fewer pregnant women are covered, "we're going to see a huge uptick of emergency room utilization, a huge decrease in preventative care and early detection," during pregnancy, Ali told Live Science.

Racial disparities

The same groups that may lose the most coverage under the Medicaid cuts are also those that are at higher risk of poor outcomes for mom and baby. Black and Native American women are two to three times more likely than white women to die during pregnancy, childbirth and the postpartum period, according to KFF.

Some of this disparity has to do with access to care and poorer quality of care for people of color. A 2025 study of over 3,000 hospitals showed sparser staffing and worse mortality outcomes in hospitals that served predominantly Black patients compared with hospitals with lower percentages of Black patients. And the 2021 study on maternity unit closures also found that severe maternal morbidity was worse in hospitals that served many Black patients.

Research also suggests that American Indian and Alaska Native patients face serious gaps in their health care coverage, which could prevent them from accessing lifesaving preventive care.

Racial bias by health care providers may play a role as well. A 2017 review of studies on doctor-patient communication found that Black patients experienced "poorer communication quality, information-giving, patient participation, and participatory decision-making" compared with white patients. This could lead to a lack of trust between doctor and patient that affects clinical decision-making, the study researchers wrote. For example, the doctor may view the patient as less engaged and fail to give them important recommendations about how to care for their health.

Preventable deaths

Despite big-picture problems with the healthcare system, the data suggest that there are opportunities to prevent a large number of maternal deaths.

A 2024 study in the American Journal of Obstetrics and Gynecology looked at deaths across 42 states and found that over 90% of deaths from preeclampsia and eclampsia in the U.S. could have been prevented. So could more than 80% of deaths from hemorrhage and cardiovascular conditions and about 70% of deaths from infection. Harder to prevent are deaths from stroke or amniotic fluid embolism, an emergency in which amniotic fluid enters the maternal bloodstream, but even then, 40% of deaths were found to be preventable.

The fraction of deaths that could have been prevented with immediate improvements in medical care varied dramatically among states, from 45% to 100%, the study found.

"The number one finding is this variability," said study author Dr. Andreea Creanga, a public health researcher at the Johns Hopkins Bloomberg School of Public Health.

That variability is actually a cause for hope, experts say, because it suggests there are clear measures that states, hospitals and providers can implement to reduce maternal mortality.

Learning from each death

The first step in preventing these deaths is to study each death in detail, Rainford said.

States that have studied these deaths and used those lessons to make concerted efforts to reduce maternal mortality have seen success. California's long-running Maternal Quality Care Collaborative, for example, prompted a dramatic decline in maternal mortality in the decade after it was started in 2006, putting the state almost on a par with Canada.

The collaborative helps to investigate the causes of individual deaths, looking for preventable factors. "It's transformed things," Conry said.

But current policies and politics may be hindering efforts to learn from past experiences. After the investigative news organization ProPublica reported a series of preventable maternal deaths in Texas and Georgia likely caused by hospitals delaying care out of fear that doctors would be prosecuted under the states' strict abortion laws, Georgia abruptly fired every member of its committee on maternal deaths. The state will not disclose who is now on the committee. The board in Idaho, which also has a strict abortion ban, was dissolved by state lawmakers in 2023 before being reestablished in 2024, leading to gaps in analysis and methodology changes. Texas' committee skipped analyzing deaths in 2022 and 2023, the two years after the Supreme Court overturned Roe v. Wade and enabled the state to enact laws restricting nearly all abortions.

The lack of transparency stemming from abortion politics is a barrier to reducing maternal mortality.

Standardizing care

Creating and implementing standards of care is another way to lower death rates. For instance, after the California Maternal Quality Care Collaborative analyzed maternal deaths in detail, they found a clear pattern: Too many women were dying of postpartum hemorrhage, one of the most common causes of maternal mortality.

So they provided hospitals tool kits to handle emergency scenarios, including standardized drills, training, and instructions to stock a "crash cart" of supplies to handle postpartum hemorrhage.

The same concept of standardized care could be extended to other conditions beyond hemorrhage, Conry said. For instance, the Collaborative will soon release guidance on better recognizing sepsis, a type of life-threatening infection that can occur during or after childbirth.

There is also a need to improve monitoring before labor and delivery. Over time, the immediate causes of death have been shifting from rapidly-developing emergency situations, such as hemorrhage, toward chronic conditions, such as cardiovascular disease, Creanga said.

This underscores the importance of people receiving regular care through pregnancy and for increased monitoring of high-risk individuals. For example, Johns Hopkins has launched an initiative called The Maryland Maternal Health Innovation Program (MDMOM) that includes at-home, telehealth-supported blood-pressure monitoring for pregnant patients with high blood pressure. That could help catch patients whose health is deteriorating, before an emergency happens. (The Preeclampsia Foundation offers a similar program nationwide.)

Creanga and her colleagues are also working to improve education for health care professionals and community groups around warning signs for high-risk pregnancy. The goal is to get tools into the hands of patients and their families, Creanga said, and to move the U.S. into the company of countries like Norway, where maternal death is vanishingly rare.

"Maternal mortality is a marker of the health of your country," she said. "It's maybe the most important marker."

"Getting your tubes tied" is a colloquial way to say that someone is undergoing tubal ligation, a sterilizing surgical procedure that involves closing off the fallopian tubes.

In non-medically assisted pregnancy, an egg travels from the ovary to the uterus via the fallopian tubes, also called uterine tubes. Tubal ligation prevents this movement by permanently blocking, clipping or removing the tubes, thus keeping the egg from becoming fertilized. The removal of the tubes, called a salpingectomy, is a type of tubal ligation.

The procedure is extremely effective, with a 99% free-from-pregnancy rate. That number rises to 100% for surgeries that use large incisions to access the tubes, rather than minimally invasive medical tools that can navigate the body through small incisions.

"It's a great option for family planning that does, unfortunately, involve a surgical procedure," Dr. Andrew Rubenstein, director of General Obstetrics and Gynecology at NYU Langone Health, told Live Science.

Side effects are minimal, but can include shoulder pain, bloating, abdominal cramping, nausea and dizziness, according to Cleveland Clinic. The shoulder pain is related to gas used to temporarily inflate the abdomen during some tubal ligation procedures; that gas can linger and irritate the neck, shoulders and chest for up to a couple days after surgery.

Tubal ligation can be performed whether or not the patient has had a pregnancy previously, Rubenstein explained.

Related: Tube-tying surgeries and vasectomies skyrocketed post-Roe

Regardless of when a person gets their tubes tied, extensive consultation between the patient and the physician is required beforehand. The patient's partner may also be included in the consultation, if applicable.

"It is shared decision making amongst the team members," Rubenstein said, describing the process of deciding what form of birth control is the best approach for each individual patient. "It's not a single episode event and then surgery is scheduled. It does require some doctor-patient relationship."

How does the surgery work?

There are four main methods for completing a tubal ligation, each using a different technique to block the travel of an egg. Doctors may remove both tubes completely — which is called a bilateral salpingectomy, or "bisalp" for short — or partition the tubes by cauterizing, clipping or folding them.

(Unilateral salpingectomies, which remove only one tube, are not a sterilizing procedure but can be used to treat conditions like ectopic pregnancy.)

The method a physician chooses, and whether they agree to carry out the procedure at all, in part depends on a patient's clinical history, Rubenstein said. Doctors will consider factors like age, past surgical procedures and body mass index to see what's feasible for a given patient.

The procedure is often completed through two small incisions, one just below the navel and the other on the lower abdomen above the pelvis. Using laparoscopic tools — a small camera and accompanying instruments that allow the surgeon to see within the body — the physician can complete the permanent operation.

Sometimes a tubal ligation is performed as a preventative treatment to decrease a patient's chances of contracting ovarian cancer. Evidence suggests that ovarian cancers often arise in the fallopian tubes, and that removing the tubes can cut the risk.

"It doesn't eliminate it, but it definitely reduces that risk for patients," Rubenstein said. It's currently unclear by how much tubal ligation lowers the odds of developing ovarian cancer, but some research suggests it decreases by 24% to 42%.

Anyone with fallopian tubes who is uninterested in getting pregnant in the future and already plans to undergo pelvic surgery should consider taking this preventative measure simultaneously, the Ovarian Cancer Research Alliance and the Society of Gynecologic Oncology suggest.

Rubenstein warned that not all operating rooms will perform tubal ligations. "Certain organizations will not allow you to do tubal ligation in their facilities based on religious beliefs, so they have to be done then in a nondenominational facility," he said.

Is it permanent?

Like any operation, tubal ligation can fail — in this context, failure means the patient becomes pregnant after the surgery.

"It's extremely rare," Rubenstein said, but it can happen and is more likely to occur for younger patients. Within the first year after the procedure, the failure rate is estimated to be 0.1 to 0.8% across all patients.

Some providers won't perform the procedure on someone younger than 30, Rubenstein said, on the basis that the patient might later come to regret it. One 2022 study that surveyed about 1,500 patients found that 12.6% of people who underwent sterilization at ages 21 to 30 and 6.7% of those who underwent sterilization when they were older than 30 regretted their choice. Notably, the majority of the patients — 92% — were in the over-30 group, so the sample of under-30s was somewhat small.

To place the 2022 study in greater context, the average regret rate reported is similar to that for knee replacement surgery, at around 10%.

Rubenstein thinks it is important to emphasize that tubal ligation is a permanent surgery. "People have a misconception that tying your tubes is similar to tying your shoelaces. You can tie and untie them," he said.

While it is medically possible to reverse the operation when the tubes have not been fully removed, just cauterized, clipped or folded, most doctors won't do so, Rubenstein said. When they are done, reversal surgeries enable about 73% of patients to get pregnant and 53% to give birth, a review of 135 cases found.

In contrast, Rubenstein described in vitro fertilization (IVF) success rates in such situations as "exceptional." In other words, "we would recommend to that patient to have an IVF cycle and then a transfer of that embryo into the uterus rather than trying to reconnect the tubes." IVF never requires an egg to travel through the tubes, so the procedure would still work for a person lacking tubes.

This article is for informational purposes only and is not meant to offer medical advice.

At a meeting held by the Food and Drug Administration on July 21, 2025, a panel convened by the agency cast doubt on the safety of antidepressant medications called selective serotonin reuptake inhibitors, or SSRIs, in pregnancy.

Panel members discussed adding a so-called black box warning to the drugs — which the agency uses to indicate severe or life-threatening side effects — about the risk they pose to developing fetuses. Some of the panelists who attended had a history of expressing deep skepticism on antidepressants.

SSRIs include drugs like Prozac and Zoloft and are the most commonly used medicines for treating clinical depression. They are considered the first-line medications for treating depression in pregnancy, with approximately 5% to 6% of North American women taking an SSRI during pregnancy.

We are a psychologist certified in perinatal mental health and a reproductive psychiatrist and neuroscientist who studies female hormones and drug treatments for depression. We are concerned that many claims made at the meeting about the dangers of those drugs contradict decades of research evidence showing that antidepressant use during pregnancy is low risk when compared with the dangers of mental illness.

As clinicians, we have front-row seats to the maternal mental health crisis in the U.S. Mental illness, including suicide and overdose, is the leading cause of maternal deaths. Like all drugs, SSRIs carry both risks and benefits. But research shows that the benefits to pregnant patients outweigh the risks of the SSRIs, as well as the risks of untreated depression.

The panel did not address the safety of SSRIs following delivery, but numerous studies show that taking SSRI antidepressants while breastfeeding is low risk, usually producing low to undetectable drug levels in infants.

Related: 'Love hormone' oxytocin can pause pregnancy, animal study finds

The biology of maternal brain health

Pregnancy and the months following childbirth are characterized by so many emotional, psychological and physical changes that the transition to motherhood has a specific name: matrescence. During matrescence, the brain changes rapidly as it prepares to efficiently take care of a baby.

The capacity for change within the brain is known as "plasticity." Enhanced plasticity during pregnancy and the postpartum period is what allows the maternal brain to become better at attuning to and carrying out the tasks of motherhood. For example, research indicates that during this period, the brain is primed to respond to baby-related stimuli and improve a mother's ability to regulate her emotions. These brain shifts also act as a mental buffer against aging and stress in the long term.

On the flip side, these rapid brain changes, fueled by hormonal shifts, can make people especially vulnerable to the risk of mental illness during and after pregnancy. For women who have a prior history of depression, the risk is even greater.

Clinical depression interferes with brain plasticity, such that the brain becomes "stuck" in patterns of negative thoughts, emotions and behaviors.

This leads to impairment in brain functions that are essential to motherhood. New mothers with depression have decreased brain activity in regions responsible for motivation, regulation of emotion and problem-solving. They are often withdrawn or overprotective of their infants, and they struggle with the relentless effort needed for tasks that arise with child-rearing like soothing, feeding, stimulating, planning and anticipating the child's needs.

Research shows that SSRIs work by promoting brain plasticity. This in turn allows individuals to perceive the world more positively, increases the experience of gratification as a mother and facilitates cognitive flexibility for problem-solving.

Assessing the risks of SSRIs in pregnancy

Prescription drugs like SSRIs are just one aspect of treating pregnant women struggling with mental illness. Evidence-based psychotherapy, such as cognitive behavioral therapy, can also induce adaptive brain changes. But women with severe symptoms often require medication before they can reap the benefits of psychotherapy, and finding properly trained, accessible and affordable psychotherapists can be challenging. So sometimes, SSRIs may be the most appropriate treatment option available.

Multiple studies have examined the effects of SSRIs on the developing fetus. Some data does show a link between these drugs and preterm birth, as well as low birth weight. However, depression during pregnancy is also linked to these effects, making it difficult to disentangle what's due to the drug and what's due to the illness.

SSRIs are linked to a condition called neonatal adaption syndrome, in which infants are born jittery, irritable and with abnormal muscle tone. About one-third of infants born to mothers taking SSRIs experience it. However, research shows that it usually resolves within two weeks and does not have long-term health implications.

The FDA-convened panel heavily focused on potential risks of SSRI usage, with several individuals incorrectly asserting that these drugs cause autism in exposed youth, as well as birth defects. At least one panelist discussed clinical depression as a "normal" part of the "emotional" experience during pregnancy and following birth. This perpetuates a long history of of women being dismissed, ignored and not believed in medical care. It also discounts the rigorous assessment and criteria that medical professionals use to diagnose reproductive mental health disorders.

A summary of the pivotal studies on SSRIs in pregnancy by the Massachusetts General Hospital Center for Women's Health discusses how research has shown SSRIs to not be associated with miscarriage, birth defects or developmental conditions in children, including autism spectrum disorder.

The risks of untreated mental illness

Untreated clinical depression in pregnancy has several known risks. As noted above, babies born to mothers with clinical depression have a higher risk of preterm birth and low birth weight.

They are also more likely to require neonatal intensive care and are at greater risk of behavioral problems and impaired cognition in childhood.

Women who are clinically depressed have an increased risk of developing preeclampsia — a condition involving high blood pressure that, if not identified and treated quickly, can be fatal to both mother and fetus. Just as concerning is the heightened risk of suicide in depression. Suicide accounts for about 8% of deaths in pregnancy and shortly after birth.

Compared with these very serious risks, the risks of using SSRIs in pregnancy turn out to be minimal. While women used to be encouraged to stop taking SSRIs during pregnancy to avoid some of these risks, this is no longer recommended, as it exposes women to a high chance of depression relapse. The American College of Obstetricians and Gynecologists recommends that all perinatal mental health treatments, including SSRIs, continue to be available.

Many women are already reluctant to take antidepressants during pregnancy, and given the choice, they tend to avoid it. From a psychological standpoint, exposing their fetus to the side effects of antidepressant medications is one of many common reasons for women in the U.S. to feel maternal guilt or shame. However, the available data suggests such guilt is not warranted.

Taken together, the best thing one can do for pregnant women and their babies is not to avoid prescribing these drugs when needed, but to take every measure possible to promote health: optimal prenatal care, and the combination of medications with psychotherapy, as well as other evidence-based treatments such as bright light therapy, exercise and adequate nutrition.

The panel failed to address the latest neuroscience behind depression, how antidepressants work in the brain and the biological rationale for why doctors use them in the first place. Patients deserve education on what's happening in their brain, and how a drug like an SSRI might work to help.

Depression during pregnancy and in the months following birth is a serious barrier to brain health for mothers. SSRIs are one way of promoting healthy brain changes so that mothers can thrive both short- and long-term.

Should the FDA, as a result of this recent panel, decide to place a black-box warning on antidepressants in pregnancy, researchers like us already know from history what will happen. In 2004, the FDA placed a warning on antidepressants describing potential suicidal ideation and behavior in young people.

In the following years, antidepressant-prescribing decreased, while the consequences of mental illness increased. And it's easy to imagine a similar pattern in pregnant women.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

For the first time, scientists have captured a real-time view of a human embryo implanting in a laboratory model of a uterus.

Being able to witness the complex implantation process may be helpful for advancing fertility procedures, such as in vitro fertilization (IVF), the researchers say.

"We have observed that human embryos burrow into the uterus, exerting considerable force during the process," study co-author Samuel Ojosnegros, principal investigator for the Bioengineering for Reproductive Health Group at the Institute for Bioengineering of Catalonia (IBEC) in Spain, said in a statement. "It is a surprisingly invasive process."

In a study published Friday (Aug. 15) in the journal Science Advances, the researchers detailed their invention of an apparatus that enabled them to record a video showing how human embryos implant. The process let them measure the force exerted during implantation and see how it differs between human and mouse embryos.

During implantation, mammalian embryos attach to the endometrium — the lining of the uterus — and then begin to develop and give rise to more and more cells. Sometimes, though, this biological process doesn't work as expected. "Implantation failure is one of the main causes of infertility, accounting for 60% of miscarriages," the researchers wrote in the study.

Studying how embryo implantation works in humans is difficult in part because it requires capturing a short moment in time inside a complex organ. Capturing that fleeting moment would be especially difficult inside a person — for instance, a patient undergoing IVF — given that it could be risky to disrupt the reproductive system at that time.

Related: Should we rethink our legal definition of a human embryo?

As such, the only footage of human implantation captured before the new study was a series of still images of embryos at specific moments in the process and in a simple laboratory model of the uterine environment.

Now, researchers at IBEC have developed a way to capture the implantation of a human embryo in four dimensions. First, they created a gel made of various proteins in uterine tissue, including collagen, and put early-stage embryos in the gel. The embryos used in this study were donated by couples undergoing IVF.

This setup enabled the team to use microscopy and fluorescence imaging techniques to record the embryos' implantation into the gel. When watching the implantations, they discovered that, after releasing enzymes that broke down the uterine tissue, the human embryo invaded the uterus.

"The embryo opens a path through this structure and begins to form specialised tissues that connect to the mother's blood vessels in order to feed," Ojosnegros said. (Research done by other labs has detailed how the placenta — the temporary organ that supplies oxygen and nutrients to the fetus — similarly invades a major maternal artery in order to form in early pregnancy.)

They also found that the burrowing embryo exerted force on the uterus, essentially moving and reorganizing the tissues. The embryos also appeared to respond to external forces that they encountered, such as the addition of other cells and structures into the goo. "We hypothesize that contractions occurring in vivo [in the body] may influence embryo implantation," study co-author Amélie Godeau, a researcher at IBEC, said in the statement.

These contractions may hold one key to successful implantation, the researchers suggested in the study. The human uterus spontaneously contracts one to two times per minute, on average, and the nature of these contractions changes throughout the menstrual cycle. A previous study found that people with too many or too few uterine contractions on the day of embryo transfer in IVF had lower implantation rates than people with a "just right" amount.

"This suggests that there may be an optimal frequency range favorable for embryo implantation," the researchers wrote. The exact role of uterine contractions in successful implantation is still being studied, though.

A better understanding of the complexity of the human uterus and the process of implantation may lead to better IVF outcomes in the future, the study authors proposed.

This article is for informational purposes only and is not meant to offer medical advice.

Morning-after pills — perhaps best known by the brand name Plan B — are emergency contraceptives that can help prevent pregnancy after unprotected sex. However, myths and misinformation abound about how these medications exert their effects in the body.

So, how do morning-after pills actually work?

These medicines work by either inhibiting or delaying ovulation, the process during which an ovary releases an egg that could then be fertilized, if it encounters sperm.

Two types of morning-after pills are available in the United States: one containing progestin, a synthetic form of the hormone progesterone that regulates the menstrual cycle, and the other containing anti-progestin, which blocks progesterone receptors. Plan B is an example of the former type, while ella is an example of the latter. Both mechanisms keep the egg in the ovary longer than it would normally stay there.

"Even though there's sperm in the vagina and in the uterus after sex, it doesn't actually meet with the egg because the egg is safe inside the ovary," explained Dr. Colleen Denny, an obstetrician-gynecologist and director of the family planning service at NYU Langone Hospital in Brooklyn.

Because the pills delay ovulation, they aren't effective if an egg has already been released. That's why doctors advise users to ingest the pills as soon as possible after unprotected sex — you want to try to catch the window before ovulation begins.

"Although the morning-after pill is kind of a catchy name for emergency contraception, it’s actually misleading since emergency contraception works best if you take it as soon as possible after unprotected sex," Dr. Alison Edelman, an obstetrician-gynecologist and professor of obstetrics and gynecology at Oregon Health & Science University, told Live Science in an email.

Related: Male birth control pill passes early safety test, with more trials underway

Is one pill safer or more effective than the other?

Most morning-after pills are of the synthetic progestin variety, which are available at pharmacies with no age restrictions and without a prescription. The only anti-progestin pill in the U.S. — ella — is also available to all ages but requires a prescription.

Side effects common to both pills include abdominal and menstrual pain, dizziness, headache and nausea, which emerge due to how the pills temporarily alter hormonal signaling. It is "extremely difficult to hurt yourself" with medications that affect progesterone signaling, Denny told Live Science. "They don't cause blood clots. They don't cause dangerous side effects."

Both types of pills may delay menstruation, but that's no cause for concern, Denny said. The morning-after pill can even be taken multiple times in the same cycle without causing harm because the mechanism it uses has no long-term side effects, studies have found.

Progestin pills, like Plan B, can reduce the chance of pregnancy by 81% to 90% when taken within three days of unprotected sex. The effectiveness of the pill falls the further out from sex it's taken, meaning it's more effective if taken within one day than it is two or three days out.

By comparison, anti-progestin pills, like ella, can lower the change of pregnancy by about 85% if taken within five days. "It can be taken up to 5 days after unprotected sex with no decrease in effectiveness," and works better than progestin pills "when taken as directed," according to the American College of Obstetricians and Gynecologists (ACOG).

Anti-progestin pills can still be effective five days after sex because they can prevent ovulation both before and after luteinizing hormone — which signals the start of ovulation to the body — is released. As long the pills are ingested before the hormone peaks and an egg is released, anti-progestin pills can be effective.

Can BMI change the efficacy of morning-after pills?

It's important to know that the efficacy of morning-after pills can vary depending on the body mass index (BMI) of the person ingesting the medicine. Numerous studies have shown that emergency contraceptive pills are less effective as the user's BMI increases.

Regarding progestin pills, studies have generally shown that the pills' effectiveness dips in people with BMIs over 30, which is in the "obese" range, though select studies show dips at BMIs of 25, in the "overweight" range. Some studies have found that people with a BMI over 30 have four times the chance of getting pregnant after taking progestin-based emergency contraceptives, compared to people with BMIs under 25, in the "healthy" or "underweight" range.

Anti-progestin pills have been shown to be more effective than progestin pills for people with higher BMIs. Recent research suggests ella's effectiveness starts to fall at BMIs of 35 or higher.

The exact reason that the pills work differently at higher BMIs is not yet clear.

"We don't really know why" the efficacy is BMI dependent, Denny said. Some experts think that the amount of fat issue in the body may impact the concentrations of the medicines in the blood, while others suggest that irregular ovulation rates associated with higher BMIs could complicate research data. However, neither of these explanations is conclusive.

Additionally, in 2022, Edelman led a clinical trial testing whether a higher dose could help counter this phenomenon, but didn't find that higher doses improved the efficacy.

Despite these possible efficacy differences, doctors still suggest that anyone worried about pregnancy after unprotected sex take the morning-after pill regardless of BMI.

"If that is what someone has available and they have unprotected sex, then they should take it," Edelman said. "It won't hurt but it might help."

Related: BMI should be replaced, experts argue — here's what the alternative could be

Is Plan B an abortion pill?

The most common misunderstanding about the morning-after pill, Edelman said, "is that emergency contraception is the same thing as a medical abortion." In short, they are not the same.

"Emergency contraception is preventing a pregnancy — you take it before you are pregnant," Edelman emphasized.

Denny said she has known patients and even other doctors to mix up emergency contraceptives with other pills related to reproductive health care. "They are totally different medicines, but they're all pills, and so sometimes people get a little confused in the conversation because they're all sort of swirled together in the news stories," she said.

Morning-after pills are taken after sex but before pregnancy occurs. By comparison, birth control pills are taken routinely to regulate the menstrual cycle on an ongoing basis and lower pregnancy risk, and abortion pills are taken after a pregnancy has begun. If you are already pregnant and you take Plan B, nothing would happen to the pregnancy, Denny said.

Edelman recommends that anyone who could become pregnant should keep emergency contraception like the morning-after pill at hand. They usually last several years unopened at room temperature, and exact expiration dates can be found listed on the packaging.

An alternative form of emergency contraceptive is more invasive than a pill but also more effective. A copper intrauterine device (IUD) requires a procedure to be placed inside the uterus, but is more than 99.9% effective at preventing pregnancy if placed within five days of unprotected sex.

The effectiveness of IUDs are also not affected by BMI. "They work better than the pill for everybody, but they especially work better for people who have a higher BMI," Denny said. "And many people keep it for years after they use it for emergency contraception," as a form of ongoing birth control.

This article is for informational purposes only and is not meant to offer medical advice.

An experimental, hormone-free male birth control pill has just passed its first safety test in humans.

The trial included 16 people and was only intended to test whether the drug reached adequate levels in the body, as well as whether it triggered any serious side effects, such as concerning changes in heart rate, hormone function, inflammation, mood or sexual function.

Across the doses tested, no significant side effects were observed. That result tees up the pill to be tested in larger trials that will now look at both safety and efficacy.

The results of the early safety trial, published Tuesday (July 22) in the journal Communications Medicine, are a critical first step toward getting the pill approved, Dr. Stephanie Page, an endocrinologist at the University of Washington School of Medicine who wasn't involved in the study, told Scientific American. "We really need more reversible contraceptive methods for men," she added.

For the moment, the only male birth control options are condoms and vasectomies. The latter can be reversed, but the actual success rate of the reversal procedure varies widely in terms of how likely a person is to conceive a child afterward. If approved, the new pill would be the first drug in its class.

"A safe and effective male pill will provide more options to couples for birth control," Gunda Georg, a professor in the University of Minnesota College of Pharmacy, where the drug molecule was developed, said in a statement released earlier this year following promising preclinical testing of the pill. Columbia University was also involved in the drug's development, along with the company YourChoice Therapeutics, which is overseeing the trials.

Related: Why is there still no male birth control pill?

"It will allow a more equitable sharing of responsibility for family planning and provide reproductive autonomy for men," Georg said.

How the male birth control pill works

The experimental pill, called YCT-529, is designed to pause sperm production by interrupting specific signals in the body.

Specifically, the drug works by blocking a protein called "retinoic acid receptor alpha," which is known to play a key role in the formation and maturation of sperm. In the testes, the receptor would usually be activated by the insertion of a "key" — a vitamin A metabolite — but the drug stops this key from clicking into place. That, in turn, prevents the chain reaction that ends with sperm being made.

Finding a compound with this effect required the scientists to closely examine the structure of the receptor when it's bound to its key, as well as test dozens of molecules to see which could block the interaction.

In preclinical tests with male lab mice, the drug "elicited profound effects" on sperm production. It triggered reversible infertility within four weeks of use, showing 99% effectiveness at preventing pregnancy in the female mice the treated males mated with. When taken off the drug, the male mice's fertility was restored within about four to six weeks.

Further tests in nonhuman primates returned similar results, with sperm counts falling dramatically within two weeks of starting the drug and fully recovering within 10 to 15 weeks of stopping the drug. These preclinical tests set the stage for the recent clinical trial in people.

The trial included 16 males ages 32 to 59, all of whom had previously undergone vasectomies. This was done out of an abundance of caution, in case the experimental drug was to have any lasting impacts on fertility, Nadja Mannowetz, co-founder and chief science officer of YourChoice Therapeutics, told Scientific American.

The participants were split into groups who received either placebo pills or a low or high dose of the drug. Most of the participants took the pill only after a period of fasting, but a subset were also given doses after a large meal, to see if that affected levels of the drug in the body.

Across all of the doses and conditions tested, the levels of the drug in the body reached decent levels, but Mannowetz anticipates that, if approved, the final dose would be closest to the highest one tested: 180 milligrams.

Both the animal study and the human trial results suggest that the approved pill would likely be taken once a day, but further trials will confirm that dosing. And although no notable side effects emerged in this small trial, future trials with larger study cohorts will still need to monitor for these effects.

"The positive results from this first clinical trial laid the groundwork for a second trial, where men receive YCT-529 for 28 days and 90 days, to study safety and changes in sperm parameters," the study authors wrote in their paper. That trial is already underway and again is looking at males who have already had vasectomies or who have made a firm decision not to father children.

This article is for informational purposes only and is not meant to offer medical advice.

It's a commonly held belief: Sperm cells are like runners in an epic race, competing against each other for access to the coveted egg at the finish line. The egg, in turn, waits patiently for the winning sperm to pierce its outer membrane, triggering fertilization. This narrative of racing sperm and waiting eggs has persisted through time — and yet, it simply isn't accurate. Scientific research has debunked this idea time and time again.

In her new book "The Stronger Sex: What Science Tells Us about the Power of the Female Body" (Seal Press/Hachette, 2025), science writer Starre Vartan addresses this and other pervasive myths about the female body, highlighting what science actually tells us about differences in biology between the sexes and where gaps in knowledge still exist, in part, due to a historic lack of research focused on females.

Eggs are choosy (but we keep forgetting)

Making all your eggs at once, stress-testing and dumping most of them, and having one available at a time for fertilization is a mammalian adaptation. It represents a shift in reproductive strategy, according to Professor Lynnette Sievert, a biological anthropologist at the University of Massachusetts, Amherst. That shift is away from an earlier, or more ancient method of reproduction, which fish, amphibians, and most reptiles still employ today to great success.

They both make both eggs and sperm continually, in great quantities, and throughout their lifetimes until they die. Female fish and frogs expel their masses of eggs into the water, and the males shoot, deposit, or generally aim their sperm in the eggs' direction. The eggs that get fertilized then develop — or don't, due to environmental conditions, or get eaten by predators. Sea turtles have sex, but still lay hundreds of fertilized eggs at a time and do so until they are elderly, as do oviparous snakes (viviparous snakes give birth to live young).

For all these animals, reproduction is a numbers game. Lots of eggs, lots of sperm, plenty of fertilized eggs and hatchlings, with just a few young surviving to adulthood. In many cases the newly hatched turtles, tadpoles and wee snake-babies are an important food source for other animals who live in their ecosystem, like a biological offering to the greater community.

This more-reproductive-stuff-is-better design is still employed by male humans, but not females.

Related: Do sperm really race to the egg?

"Human males still follow the fish pattern. They're still putting out a million sperm. They're not cleaning the sperm, they're not putting out the best sperm, they're just putting out all the sperm just like a fish," Sievert says. She wonders why then, female mammals made a significant shift away from that model. "Why was there never a selection on male sperm and mammals to be like eggs? Something shifted, that separated the sexes," she says. It's an unanswered biological question, but there is one obvious possible answer: Control.

Female mammals house the mechanisms over which eggs (and sperm) are used for reproduction inside their bodies, while amphibians, reptiles, and fish let outside ecological conditions like temperature, predators, salinity and pollutants decide who lives and dies. Both strategies are clearly effective, but why would mammals have shifted away from a successful model?

It could be that longer-lived mammals are able to store epigenetic information about local conditions as they grow, which could influence when and which eggs and sperm are chosen. The choices about who lives and who doesn't are made before or during conception, instead of after, resulting in offspring that are best suited to current conditions.

Why all this trouble to "turn your body into an eggshell," as Cat Bohannon puts it in her book "Eve: How the Female Body Drove 200 Million Years of Evolution" — when the eggshell, or other reproductive strategies work so well? It could be explained by a combination of energetics and fine-tuning. By bringing fertilization and growing their young inside the female body, mammals can then use their lived experience (not just conditions at the moment of conception) to affect which traits are selected for. They can do this by controlling both which egg and which sperm are preferred.

All this energy being used at or before the stage of conception means there are fewer fertilized eggs, and fewer babies. When you only have a baby or two at a time, instead of hundreds, it then becomes logical to invest in ensuring it has the best chances of survival — so an egg battle and a female body that's choosy about sperm makes total sense. As do the years of parenting that follow.

That eggs choose sperm is a basic biological fact that has been "discovered" quite a few times over the years. The stubbornness of the "active sperm and waiting egg" story despite the facts highlights how hard it is for humans to accept biological narratives that run counter to our cultural ideas.

As Emily Martin detailed in her memorable paper, we know that it was once the narrative that the sperm was the active party in fertilization, with all the speedy, tough sperm out swimming each other and trying to be the first one to attack the egg's outer membrane to gain entry and deposit their DNA packages.

Way back in the mid-1980s, it was first discovered that the egg was actually the active decider in fertilization. The egg does this by using its zona pellucida (a thick protein coat that protects the egg cell) to chemically grab onto sperm, test it, and then reject or admit its DNA into the egg. The sperm, wiggling back-and-forth, can't break even a single chemical bond, but the egg can. Research in the 1990s went on to support the idea, and it's widely accepted.

Yet, over the last 20 years, scientists continue to "discover" this fact. In 2017, Quanta magazine published an article^⁠ about a researcher whose work was "challenging this dogma" that "the egg is not the submissive, docile cell that scientists long thought it was" and in 2019, a University of Virginia magazine article stated: "The old notion of the egg as a passive partner for sperm entry is out. Instead, the researchers found, there are molecular players on the surface of the egg that bind with a corresponding substance on the sperm to facilitate the fusion of the two." The writer called this an "unexpected discovery."

This "rediscovery" of already known scientific information about the egg and sperm's interaction was covered by a Ms. Magazine article in 2024 about Evelyn Fox Keller, a pioneer in the field of feminist philosophy of science. The passive egg/active sperm idea just wouldn't go away, even in the same journals that published the research that it wasn't true. "One of Fox Keller's key findings was that seemingly neutral assumptions in biology can in fact be gendered. Keller's informed social analysis of the sciences paved the way to approach science as a cultural phenomenon." That researchers and the science press are repeating the same "discoveries" for decades shows just how gendered ideas stick to the culture, and can hold science back.

The newest evidence shows that not only does an egg decide which sperm it wants to admit, the egg may be attracting or repelling different sperm even before they make it to the egg.

In 2020, scientists at Stockholm University collaborating with colleagues at the University of Manchester found that eggs release a chemical that can attract sperm as it makes its journey. They also found that different eggs attract different varieties of sperm — not all eggs attracted the same sperm. The eggs sometimes attracted sperm that was not their partner's.

They figured this out by obtaining reproductive material from couples who gave them permission to at an IVF clinic in Manchester, U.K. "Each experimental block comprised the follicular fluid and sperm samples from a unique set of two couples, exposing sperm from each male to follicular fluid from their partner and a non-partner," the researchers wrote of their methods.

Chemosensory communication between eggs and sperm allows "female choice and bias fertilizations toward specific males," the researchers wrote. What are the egg's criteria? It's unknown at this point. It could be selecting higher-quality sperm or sperm that's more genetically compatible in some way. "This shows that interactions between human eggs and sperm depend on the specific identity of the women and men involved," one of the researchers told Labroots. He went on to say that the choice of sperm was entirely up to the egg.

The science shows that contrary to some cultural stories, the menstrual cycle is highly sensitive to conserve energy; eggs go to war each month so that only the strongest survive; that winner egg sends out come-hither signals to sperm it likes; and then it chooses which sperm to unite with to make a possible new human being.

So much for the inherent weakness of women's bodies and the passive female reproductive system.

Scientists may be one step closer to understanding why polycystic ovary syndrome (PCOS) tends to run in families.

The new research, presented July 1 at the 41st Annual Meeting of the European Society of Human Reproduction and Embryology in Paris, suggests that "disruptions" in the way genes are turned on and off may increase the likelihood of developing PCOS. These "epigenetic" changes alter gene activity without changing DNA's underlying code, but they may also be passed down through families.

In theory, this research hints at a potential avenue for preventing PCOS.

If a person was undergoing in vitro fertilization (IVF), for example, "these damaging [epigenetic] markers may be identified in embryos and changed before being implanted in a pregnant person, preventing PCOS from being passed onto future offspring," Dr. Sherry Ross, a board certified OB/GYN at Providence Saint John's Health Center in Santa Monica, California, told Live Science in an email.

However, "further research needs to be done in human embryos to understand if this is a safe and viable intervention," she added.

Understanding PCOS inheritance

PCOS is a hormonal condition that affects 6% to 13% of reproductive-age women, according to the World Health Organization (WHO). Many cases — up to 70% — go undiagnosed worldwide. Common symptoms include ovarian cysts, weight gain, balding or thinning hair on the head, excess hair on the face or body, acne, infertility, and irregular or heavy periods.

Related: Malaria drug may treat root cause of PCOS, early study hints

Alongside these often debilitating symptoms, people with PCOS are also more likely to develop a variety of other conditions, including high blood pressure, type 2 diabetes and endometrial cancer, the WHO notes.

It's known that PCOS has a strong genetic component, said Dr. Sydney Chang, founding partner and medical director of CCRM Fertility of Austin.

In the Dutch Twin-Family Study, for example, researchers compared identical twins (who share nearly 100% of their DNA) with fraternal twins (who share 50% of their DNA), to see how likely it was for both twins in a pair to have PCOS. They found this concordance was twice as high among identical twins than fraternal twins, "suggesting that a large portion of the risk of developing PCOS is due to inherited genes," Chang told Live Science in an email.

It's estimated that 20% to 40% of people with PCOS have a mother or sister with the condition. But the exact pattern of inheritance is unclear, Chang noted. On that front, the new research may shed some light.

The study, led by Dr. Qianshu Zhu, an assistant professor of reproductive biology at the Institute of Reproductive Medicine at Chongqing Medical University in China, included about 230 women undergoing IVF, 133 of whom had PCOS and 95 of whom didn't. The researchers looked at unfertilized egg cells and pre-implantation embryos from these participations, looking for chemical tags, known as epigenetic markers, on the cells' DNA. These markers affect the activity of the genes they're attached to.

Compared to the eggs and embryos of people without PCOS, those from participants with the condition showed "widespread disruptions" in many key genes, according to a statement. Affected genes were involved in metabolic processes and activation of the early embryo's DNA. Sections of the genome called retrotransposons, which must be tightly regulated to keep DNA stable, were also affected.

The team also noted irregular patterns in well-known epigenetic markers that help control genes, including one called H3K27me3. In the statement, Zhu noted that "about half of the abnormal H3K27me3 signatures we saw in Day 3 embryos were already present in the oocyte [egg cells]. This tells us that an epigenetic signal is being passed from mother to embryo before implantation even begins."

Understanding these mechanisms could enable new preventative interventions for PCOS. The authors suggested that embryos created through IVF could potentially be treated to tweak their epigenetics and thus lower the risk of PCOS being inherited. The findings could also be useful in aiding embryo selection processes in IVF, they added.

Zhu emphasized, however, that the research is based on only lab-made embryos and cannot demonstrate how these epigenetic markers affect children. His team is now pursuing mouse studies to better understand the potential effects in offspring.

"What is exciting about this new research is it supports an actual genetic association between PCOS in families," Ross said, "and shines light for early diagnosis and interventions to prevent PCOS from being transmitted through families."

This article is for informational purposes only and is not meant to offer medical advice.

Researchers have developed a new laboratory model grown from stem cells that replicates the human amniotic sac in the first two to four weeks after fertilization.

The structure, which the researchers say is the most advanced and mature amniotic model ever created, could offer new insight into human development and lead to cell products for medical procedures, from burn treatments to cornea reconstruction, the team reported in a study published July 10 in the journal Cell.

The growing human embryo isn't alone on its developmental journey. "Supporting tissues like the placenta, like the amniotic sac, grow with the embryo and are really important for the embryo's growth and survival," said study co-author Silvia Santos, a group leader at the Francis Crick Institute in London.

The amniotic sac is a fluid-filled, biological balloon that cushions and protects the growing embryo. The liquid it contains is thought to be essential for healthy embryo development. But it hasn't been easy to investigate this interplay between the embryo and its entourage, largely because this stage of development is logistically difficult and ethically fraught to study inside human beings.

Previous attempts at modeling the amniotic sac in the lab were unable to replicate its complex 3D structure, which has two distinct cell layers. In addition, previous models tended to last only a few days, making it harder to get insight into the extended process of development.

By contrast, Santos' new cell models, called post-gastrulation amnioids (PGAs), can survive in their lab dishes for at least three months and develop to the same degree as a month-old amniotic sac. Remarkably, they grow to a similar size, too — up to about an inch (2.5 centimeters).

Related: Scientists invent 1st 'vagina-on-a-chip'

"They are little golf balls," Santos told Live Science. The PGAs also form the amniotic sac's distinct two-layer structure.

To achieve this, Santos' team used a new cell-culture method. They began with embryonic stem cells, which can grow to become any other cell type in the body if nudged with specific signaling molecules. The team exposed these cells to two of these signals, called BMP4 and CHIR. They made sure to space out the signals, adding BMP4 over the first 24 hours of growth, followed by CHIR for another 24 hours.

Then, the researchers left the cells alone in round-bottomed culture dishes. "The rest was complete self-organization," meaning the maturing stem cells orchestrated their own assembly into a structure, Santos said.

Single cells aggregated in the dishes and formed the distinct two-layered, fluid-filled structure the team had searched for. "This just shows you that these embryonic stem cells have this amazing propensity to specialize and to become everything given the right instructions, which I'm still in awe about," Santos said.

Armed with their new models, the team set out to answer key questions about how amniotic sacs influence their environment. They wanted to know what genes might be directing cells to turn into PGAs. By interfering with a long list of genes that they suspected might influence cell development, they found that a single gene, GATA3, could convert cells into amniotic sacs without any other signals.

GATA3 codes for a transcription factor — a protein that turns other genes on or off. Santos and her team showed that two of the genes GATA3 regulates are BMP4 and CHIR, the same genes their culture protocol had involved.

To explore how the amniotic sac may influence nearby cells, they mixed their PGAs with additional stem cells that hadn't been nudged to become any particular cell type. Left on their own, these cells would have continued to exist in their unspecialized state. But next to the PGAs, they changed into a host of other "extraembryonic" cell types, showing that the amniotic sac was capable of driving the transformation of cells around it.

Santos and her team are now exploring possible applications for their new system. Amniotic sacs have antimicrobial and anti-inflammatory properties, and people who have had elective C-sections can opt to donate their amniotic sacs for use as transplant tissue in burn treatments or cornea repairs. These donated materials can be difficult to standardize, Santos said, but PGAs could theoretically provide a reliable source of these desired cells.

Yi Zheng, an assistant professor in biomedical and chemical engineering at Syracuse University who was not involved in the study, said further tests would be required to see whether PGAs could provide clinically useful materials for such procedures.

He added that mature, non-stem cells can be transformed back into stem cells called induced pluripotent stem cells (iPSCs). Perhaps, Zheng said, iPSCs converted into PGAs could be particularly useful for medical applications, in part because you could use a patient's own cells to generate them.

Better models of the amniotic sac could also help researchers understand why this critical structure sometimes malfunctions. Some congenital disorders — meaning those babies are born with — are tied to differences in the size or content of the sac prior to birth, and Santos said the PGAs could help explain that link.

"I'm extremely excited about the potential of these little structures," she concluded.

Early data hint that the common diabetes drug metformin may greatly reduce the risk of a severe form of morning sickness that affects thousands of pregnant people each year.

This form of morning sickness — called hyperemesis gravidarum (HG), or hyperemesis — can lead to complications during pregnancy, such as weight loss, dehydration and electrolyte imbalance, as well as long-term health issues for both mother and baby. It's also common for people who had hyperemesis in their first pregnancy to experience it again in subsequent pregnancies.

Previous research had established that people who are genetically predisposed to hyperemesis often have lower levels of a hormone called "growth and differentiation factor 15" (GDF15) prior to pregnancy. During pregnancy, the placenta makes GDF15, which is beneficial to the survival and growth of the fetus. Having low pre-pregnancy GDF15, the theory goes, makes individuals more sensitive to the hormone's rapid rise in pregnancy, triggering extreme nausea and vomiting.

Meanwhile, metformin, a drug commonly used to treat type 2 diabetes, is known to raise levels of GDF15 in all users, and this is thought to reduce appetite and promote weight loss. Knowing this link to GDF15, researchers explored whether metformin could "train" the body to tolerate the hormone before pregnancy.

Their survey-based study, published June 27 in the American Journal of Obstetrics and Gynecology, showed that when taken before pregnancy, metformin reduced the risk of hyperemesis by more than 70%.

If confirmed through further studies, this approach to hyperemesis prevention "would be a game changer," said Dr. Andrew Housholder, an emergency physician specializing in hyperemesis who was not involved in the study.

Related: We may finally understand how metformin lowers blood sugar, animal study finds

"HG patients often change their family planning due to the severity of their illness with prior pregnancies," Housholder told Live Science in an email. "Allowing a person to have a normal pregnancy, without the severe symptoms and weight loss, is very meaningful."

For the study, researchers recruited more than 5,400 participants who visited the Hyperemesis Gravidarum Education and Research Foundation's social media platforms. These people were asked to fill in an online questionnaire. Respondents reported their daily use of 32 common substances, including prescribed medications and recreational drugs, in the month before each pregnancy, along with their level of nausea and vomiting during pregnancy.

Metformin use before pregnancy was linked to a more than 70% reduction in the risk of hyperemesis in first pregnancies and an 82% risk reduction in second pregnancies, the survey suggested. Additionally, tobacco use before pregnancy was associated with a 49% lower risk of experiencing hyperemesis — although the drug of course ups the risk of other serious pregnancy complications.

In contrast, pre-pregnancy use of selective serotonin reuptake inhibitors (SSRIs), a common class of antidepressants, was associated with increased risk of hyperemesis in both first and second pregnancies. Cannabis use was associated with increased risk in only second pregnancies.

"The large reduction in risk [tied to metformin] identified provides strong evidence to support that pre pregnancy metformin treatment can provide a benefit," study co-author Marlena Fejzo, a medical scientist at the Keck School of Medicine of the University of Southern California, told Live Science in an email.

While the findings are promising, they are based on self-reported data in a highly selective population, noted Dr. Stephen O'Rahilly, a professor of clinical biochemistry and medicine at the University of Cambridge in the U.K. who was not involved in the study. A clinical trial is now needed to confirm whether prescribing metformin before pregnancy could effectively prevent hyperemesis, O'Rahilly told Live Science in an email.

Clinical trials will also need to measure how the dose of metformin and timing of administration impacts outcomes, study co-author Dr. Aimee Brecht-Doscher, an OB/GYN physician at Ventura County Health Care Agency in California, told Live Science in an email.

Metformin is safe to take during pregnancy and many users take it throughout pregnancy to treat diabetes, Brett-Doscher noted. But notably, the study didn't look at what effect the drug might have on morning sickness at that juncture or how many participants went off the medication post-conception.

For people who don't already take metformin prior to pregnancy, it may be that the drug would come too late to help stave off hyperemesis. However, it could theoretically be used to prevent hyperemesis in subsequent pregnancies. But again, this would need to be confirmed in trials.

"Women who've had HG once are likely to have it again," Brecht-Doscher said. "Many, having been traumatized by the experience, decide they'll never again get pregnant. Using metformin to reduce the chances of a recurrence could give them more options."

"This study clears the way for clinical trials, because we've shown it's worth pursuing," she added.

This article is for informational purposes only and is not meant to offer medical advice.

Some early-onset cancers — those that occur in people under age 50 — are on the rise in the United States.

This overall increase is due to a rise in 14 different types of cancers in younger people, according to a new analysis. The largest increases have occurred in breast, colorectal, kidney and uterine cancer diagnoses.

While the overall incidence of early-onset cancer is still low, these small increases could add up over time.

A rise of a few percent per year is "not a huge change in the number of diagnoses, because cancer is still rare at these ages," Miranda Fidler-Benaoudia, a cancer epidemiologist at Alberta Health Services and the University of Calgary, told Live Science. "But it's when it's happening over two, three decades that it really leads to a meaningful increase in that period."

The reasons behind these increases are complex and manifold, and many are probably specific to each type of cancer, experts say.

To tease out trends in early-onset cancer diagnoses and the myriad reasons behind them, National Cancer Institute epidemiologist Meredith Shiels and colleagues compiled data on cancers diagnosed in 15- to 49-year-olds between 2010 and 2019 in the U.S. In a study published May 8 in the journal Cancer Discovery, the team broke down changes in the rates of different cancers in three age groups: 15 to 29, 30 to 39, and 40 to 49.

Breast and uterine cancer rates increased in every early-onset age group, while rates of colorectal and certain kidney cancers increased among 30- to 39-year-olds and 40- to 49-year-olds, the team found. More than 80% of the additional cancers that occurred in 2019 compared with 2010 were one of these four types. Other diagnoses that increased in at least one early-onset cohort included melanoma, cervical cancer and stomach cancer, though incidences of these cancers remained low overall.

Lifestyle changes

Many factors could contribute to these observed increases. Research suggests that obesity is a risk factor for colorectal, kidney and uterine cancers, all of which are rising in younger people. Globally, the percentage of adults who are overweight or obese has increased significantly since 1990. Although most studies linking cancer and obesity were conducted in older adults, it's possible that higher rates of obesity in younger people could also increase the rates of early-onset cancer, the researchers wrote. One 2024 study suggests that more than half of uterine cancers diagnosed in 2019 might be linked to obesity.

Changes in reproductive patterns over the years could also be contributing to the increased incidence of early-onset breast cancers, Fidler-Benaoudia said. Girls are getting their periods earlier, and women are having fewer children, and having them later in life, than they did a few generations ago. Being younger at first menstruation, giving birth fewer times, and giving birth for the first time later in life have all been linked to a higher risk of developing certain types of early-onset breast cancer, the researchers wrote. Other research suggests that using oral contraceptives (birth control pills) might also slightly elevate the risk of early-onset breast cancer, though it may also protect against ovarian and endometrial cancers.

Better detection

Earlier detection of cancers in people with genetic risk factors may also play a role. For instance, those with certain BRCA gene variants have a higher risk of breast, ovarian or prostate cancer, while those with Lynch syndrome face an increased risk of myriad cancers, including colon cancer, stomach cancer and brain cancer.

Newer screening guidelines recommend people with these genes start screening for cancer earlier than those with an average risk of the disease. Even a small increase in the number of early-onset cancers detected via these new recommendations could trigger an uptick in diagnoses.

Screening for other, unrelated issues could also help identify certain cancers earlier. For example, changes in imaging procedures for MRIs and CT scans mean that health care professionals are catching more instances of renal cell carcinoma, a type of kidney cancer, during other tests. This incidental detection has led to an increase in kidney cancer diagnoses in almost all age groups, the researchers wrote.

Environmental exposures

People's prenatal or early-life exposures to certain compounds may also fuel specific early-onset cancers. Researchers reported in April in the journal Nature that childhood exposure to a chemical called colibactin, which is produced by certain E. coli strains in the colon, causes DNA mutations observed more frequently in early-onset colorectal cancers.

Showing that an exposure directly causes a certain type of early-onset cancer — or even pinpointing which types of exposures might pose a risk — is no easy feat. "I think that we need large studies that follow individuals over the life course, including at younger ages, to be able to identify risk factors for early-onset cancers," Shiels told Live Science in an email.

Even with these sorts of extended studies, though, it can be challenging to pin down the exact causes of early-onset cancer. "The issue with cancer at young ages is, whilst it's increasing, it's still relatively rare [compared] to those older age groups," Fidler-Benaoudia said. "To have enough people develop cancer to then identify risk factors in this prospective way is incredibly challenging, because you need huge, huge numbers."

While it's impossible to eliminate your individual risk of getting cancer, there are some things that reduce the overall risk at the population level. For instance, wearing sun protection and getting vaccinated against human papillomavirus (HPV) can help protect against certain cancers, Fidler-Benaoudia said. Similarly, limiting alcohol and smoking can reduce the odds of a person developing cancer at any point in their life, not just before age 50, Tomotaka Ugai, a cancer epidemiologist at the Harvard T.H. Chan School of Public Health and Brigham and Women's Hospital, told Live Science.

Male fertility rates have been plummeting over the past half-century. An analysis from 1992 noted a steady decrease in sperm counts and quality since the 1940s. A more recent study found that male infertility rates increased nearly 80% from 1990 to 2019. The reasons driving this trend remain a mystery, but frequently cited culprits include obesity, poor diet and environmental toxins.

Infectious diseases such as gonorrhea or chlamydia are often overlooked factors that affect fertility in men. Accumulating evidence suggests that a common single-celled parasite called Toxoplasma gondii may also be a contributor: An April 2025 study showed for the first time that "human sperm lose their heads upon direct contact" with the parasite.

I am a microbiologist, and my lab studies Toxoplasma. This new study bolsters emerging findings that underscore the importance of preventing this parasitic infection.

The many ways you can get toxoplasmosis

Infected cats defecate Toxoplasma eggs into the litter box, garden or other places in the environment where they can be picked up by humans or other animals. Water, shellfish and unwashed fruits and vegetables can also harbor infectious parasite eggs.

In addition to eggs, tissue cysts present in the meat of warm-blooded animals can spread toxoplasmosis as well if they are not destroyed by cooking to proper temperature.

While most hosts of the parasite can control the initial infection with few if any symptoms, Toxoplasma remains in the body for life as dormant cysts in brain, heart and muscle tissue. These cysts can reactivate and cause additional episodes of severe illness that damage critical organ systems.

Related: 32 scary parasitic diseases

Between 30% and 50% of the world's population is permanently infected with Toxoplasma due to the many ways the parasite can spread.

Toxoplasma can target male reproductive organs

Upon infection, Toxoplasma spreads to virtually every organ and skeletal muscle. Evidence that Toxoplasma can also target human male reproductive organs first surfaced during the height of the AIDS pandemic in the 1980s, when some patients presented with the parasitic infection in their testes.

While immunocompromised patients are most at risk for testicular toxoplasmosis, it can also occur in otherwise healthy individuals. Imaging studies of infected mice confirm that Toxoplasma parasites quickly travel to the testes in addition to the brain and eyes within days of infection.

In 2017, my colleagues and I found that Toxoplasma can also form cysts in mouse prostates. Researchers have also observed these parasites in the ejaculate of many animals, including human semen, raising the possibility of sexual transmission.

Knowing that Toxoplasma can reside in male reproductive organs has prompted analyses of fertility in infected men. A small 2021 study in Prague of 163 men infected with Toxoplasma found that over 86% had semen anomalies.

A 2002 study in China found that infertile couples are more likely to have a Toxoplasma infection than fertile couples, 34.83% versus 12.11%. A 2005 study in China also found that sterile men are more likely to test positive for Toxoplasma than fertile men.

Not all studies, however, produce a link between toxoplasmosis and sperm quality.

Toxoplasma can directly damage human sperm

Toxoplasmosis in animals mirrors infection in humans, which allows researchers to address questions that are not easy to examine in people.

Testicular function and sperm production are sharply diminished in Toxoplasma-infected mice, rats and rams. Infected mice have significantly lower sperm counts and a higher proportion of abnormally shaped sperm.

In that April 2025 study, researchers from Germany, Uruguay and Chile observed that Toxoplasma can reach the testes and epididymis, the tube where sperm mature and are stored, two days after infection in mice. This finding prompted the team to test what happens when the parasite comes into direct contact with human sperm in a test tube.

After only five minutes of exposure to the parasite, 22.4% of sperm cells were beheaded. The number of decapitated sperm increased the longer they interacted with the parasites. Sperm cells that maintained their head were often twisted and misshapen. Some sperm cells had holes in their head, suggesting the parasites were trying to invade them as it would any other type of cell in the organs it infiltrates.

In addition to direct contact, Toxoplasma may also damage sperm because the infection promotes chronic inflammation. Inflammatory conditions in the male reproductive tract are harmful to sperm production and function.

The researchers speculate that the harmful effects Toxoplasma may have on sperm could be contributing to large global declines in male fertility over the past decades.

Preventing toxoplasmosis

The evidence that Toxoplasma can infiltrate male reproductive organs in animals is compelling, but whether this produces health issues in people remains unclear. Testicular toxoplasmosis shows that parasites can invade human testes, but symptomatic disease is very rare. Studies to date that show defects in the sperm of infected men are too small to draw firm conclusions at this time.

Additionally, some reports suggest that rates of toxoplasmosis in high-income countries have not been increasing over the past few decades while male infertility was rising, so it's likely to only be one part of the puzzle.

Regardless of this parasite's potential effect on fertility, it is wise to avoid Toxoplasma. An infection can cause miscarriage or birth defects if someone acquires it for the first time during pregnancy, and it can be life-threatening for immunocompromised people.

Taking proper care of your cat, promptly cleaning the litter box and thoroughly washing your hands after can help reduce your exposure to Toxoplasma. You can also protect yourself from this parasite by washing fruits and vegetables, cooking meat to proper temperatures before consuming and avoiding raw shellfish, raw water and raw milk.

This article was updated to remove an incorrect statement about the prevalence of deaths due to foodborne toxoplasmosis.

This edited article is republished from The Conversation under a Creative Commons license. Read the original article.

Iron deficiency during pregnancy can cause a male mouse embryo to develop female features, a new study reveals.

The low iron disrupts the activation of a key gene that spurs the development of male sex organs. This causes embryos with XY chromosomes — the most common combination seen in males — to develop female sex organs instead.

"This is a completely new and totally unexpected finding," study co-author Peter Koopman, a professor emeritus of developmental biology at the University of Queensland in Australia, told Live Science. "It's never been shown before that iron can flip such an important developmental switch."

Earlier research established that the SRY gene on the Y chromosome is the "master switch" for turning on the development of male organs in mammals. An enzyme called JMJD1A plays an important role in flipping this master switch, and it requires iron to function properly. However, the connection between iron levels and sex determination was not fully understood.

Now, in a study published June 4 in the journal Nature, researchers report that iron is essential for the development of testes in XY mice. The results show that maternal iron deficiency disrupts the activity of JMJD1A, which lowers SRY expression and drives the development of ovaries in XY mouse embryos.

However, it's too early to say whether this finding in mice might translate to human pregnancy and sex development, Tony Gamble, an associate professor of biological sciences at Marquette University in Milwaukee who wasn't involved in the study, told Live Science.

Related: Is there really a difference between male and female brains? Emerging science is revealing the answer.

In the study, the researchers used pharmaceutical treatments and low-iron diets to manipulate the iron levels in pregnant mice. When the pregnant mice experienced iron deficiency, this caused six out of 39 total XY embryos to develop ovaries instead of testes. Investigating further, they found that genetics appear to be a factor in which embryos are sensitive to this effect.

To confirm this mechanism, the team also grew embryonic gonads — structures that develop into testes or ovaries in the womb — in lab dishes so they could directly observe the impact of iron depletion. These lab analyses showed that reducing the iron in cells to 40% of normal levels led to a large increase in histones on the SRY gene. Histones are proteins that bind DNA and help control which genes are switched on, and this effect almost completely blocked the SRY gene's expression.

Normally, the JMJD1A enzyme rids the SRY gene of histones, allowing it to turn on. The researchers hypothesize that when iron levels drop, the enzyme's activity is compromised, so suppressive histones build up on the SRY gene.

These results suggest that "some important developmental traits that were previously thought to be purely genetically controlled can also be seriously impacted by nutrition and metabolic factors," Koopman said. And "if iron can have such an impact on sex development, then maybe other organ systems may also critically depend on iron or other dietary factors in a similar way," he added.

Because the research was conducted solely in mice, the question of whether iron may have similar effects in humans is still open. Although sex determination follows a broadly similar blueprint across mammals, there are some important differences between mice and humans, Gamble said.

For example, while both species rely on the same genes to drive the development of testes, the consequences of mutations in these genes differ between the two species. Their similarities to humans make mice important models for studying development and disease, Gamble said, "but the differences urge caution in simply assuming processes are acting identically across both species."

Testing the new finding in humans won't be easy, since many of the experiments possible in mice can't ethically be done in humans, Koopman said. "So, the way forward will have to involve doing biochemical, cell culture and gene expression experiments to build a body of indirect evidence that what holds true in mice is also the case in humans," he said.

Ovarian cysts are very common in people who menstruate, with an estimated 10% to 30% of women — and potentially more — developing at least one in their lifetime.

These fluid-filled sacs develop in or on the ovaries, the small organs located on each side of the uterus that produce the hormones estrogen and progesterone and release eggs each month as part of the menstrual cycle.

Most ovarian cysts form as a result of the normal menstrual cycle and don't cause any issues. However, not all ovarian cysts are the same. While some are harmless and painless, others are extremely painful and can even be cancerous. The type of cyst and its associated complications determine a person's symptoms and their course of treatment.

Learn more about ovarian cysts, why they form, and when they need treatment.

Related: Why is endometriosis so hard to diagnose?

What are the treatments for ovarian cysts?

Treatment for ovarian cysts depends on many factors, including the type of cyst, its size, and any symptoms it may be causing.

Small functional cysts often disappear on their own and don't require any medical treatment. That said, they can be regularly monitored to make sure they aren't growing.

Any minor pain associated with cysts can be treated with painkillers, like ibuprofen. However, if these symptoms don't go away or if the cyst is growing, much larger than usual, causing severe pain, or suspected to be cancerous, it may be surgically removed.

"The type and extent of surgery depends on what structures are being impacted as sometimes these cysts can affect the urinary and gastrointestinal systems," Taylor said.

Laparoscopy, also known as keyhole surgery, is generally performed if the cyst is small and benign, while laparotomy, or open surgery, may be required to remove larger cysts. The latter procedure may also be used if the cyst is suspected to be cancerous.

In rare cases, if the cyst is found to be cancerous, one or both ovaries also be removed.

This article is for informational purposes only and is not meant to offer medical advice.

Intrauterine devices (IUDs) are small contraceptive devices implanted in the uterus. They can be hormonal or nonhormonal, and they're one of the most effective options for female birth control available, with an effectiveness of over 99%. That means that, out of every 100 sexually active people who use an IUD, less than one will get pregnant per year.

IUDs are also appealing because they remain effective for a long time — three to 10 years, depending on the device.

However, even though this contraceptive method is very effective, some people might be dissuaded from getting an IUD after hearing stories from people who experienced a lot of pain when they had the device inserted.

So, how much does it hurt to have an IUD inserted? And what pain-relief methods are available for the insertion procedure?

The pain experienced during IUD insertion varies from person to person, so there's not a one-size-fits-all answer, Dr. Deborah Bartz, an associate professor of obstetrics, gynecology and reproductive biology at Brigham and Women's Hospital, told Live Science in an email. Bartz emphasized that it's important for physicians to talk to their patients about what to expect during the procedure and what their pain-relief options are.

What to expect during an IUD insertion

During an IUD insertion, a health care provider uses a medical device called a speculum to widen the walls of the vagina. The speculum itself may feel uncomfortable or put unfamiliar pressure on the vagina, but it should not be painful. Certain conditions, such as vaginismus, can make speculum insertion painful, though, so Cleveland Clinic advises patients to inform their doctors if they have any of those conditions so their providers can take extra precautions.

After inserting the speculum, the doctor uses a specialized tool to pass the IUD through the cervix — the tissue that connects the uterus to the vagina — and into the uterus. Traditionally, healthcare providers use a tenaculum, a clamp designed to hold small pieces of tissue, to cross the cervix. In recent years, some providers have instead adopted a new tool called Carevix, which uses suction to make the process of passing through the cervix less painful. Tenaculums, by comparison, slightly puncture the cervix.

In a typical case, the IUD insertion process takes less than five minutes.

IUD sizes vary by brand and type. The copper IUD, which is nonhormonal, is the largest and measures 1.3 by 1.4 inches (3.2 by 3.6 centimeters). Hormonal IUDs are smaller, with the smallest brands measuring 1.1 by 1.2 inches (2.8 by 3 cm). As an IUD is inserted, its horizontal arms fold down; once inside the uterus, the device opens into a "T" shape.

A local anesthetic is also an option. Drugs such as lidocaine can be administered topically, using a gel, cream or spray, or they can be injected directly into the local nerves. Once administered, lidocaine blocks some of the nerve signals in the cervix, thus preventing pain signals from reaching the brain.

However, even a local anesthetic may not stop pain completely, Bartz said. That's because it doesn't block pain signals from every nerve in the cervix, so patients may still feel some pressure, pain or discomfort during IUD insertion.

Some clinics offer full-body sedation during IUD insertion, but this option is less routine, Bartz said. Health care providers can use a variety of drugs to place a patient under light-to-moderate sedation, such that they are in a drowsy and relaxed state for the procedure. (Sedation is different from general anesthesia, which numbs the whole body and causes the patient to lose consciousness.)

Sedation can minimize stress and reduce pain during the insertion, but it does come with its own set of considerations. Potential side effects include disorientation, nausea and vomiting upon waking, and there is the rare possibility of having an allergic reaction to the drugs used for sedation. Notably, not all health care facilities are equipped to offer full-body sedation, as it requires an anesthesiologist on site.

Non-pharmacological options can help distract people from pain during IUD insertion, Bartz said. For instance, she gives her patients the option to bring in a support person, and encourages the patient to have a conversation during the procedure to help keep their mind off the pain. Practicing breathing techniques, listening to music or watching television may also help, studies suggest.

Listening to patients

In July 2024, the U.S. Centers for Disease Control and Prevention (CDC) updated its pain management recommendations for IUD insertions. The new guidelines call for physicians to counsel their patients on different pain management options, along with their risks and benefits. The guidelines also state that lidocaine "may be useful" to lessen pain during the insertion procedure.

"These new or lengthened conversations are certainly an improvement in care," Bartz said. Historically, research shows that providers frequently underestimate how much pain their patients experience during IUD insertion, and this underestimation likely biased their approach to pain-management counseling.

"I think, historically, women's health, including women's pain, has not been given enough attention by the medical community for a whole host of reasons," Bartz said. "With the practice of medicine moving away from a more paternalistic approach to more of a modern, patient-centered approach, I believe that there has been a greater recognition of patient discomfort and expanded conversations on ways to mitigate that discomfort."

This article is for informational purposes only and is not meant to offer medical advice.

An unsung appendage in the female body, which has long been considered useless, may actually be essential for ovary development and fertility, a new mouse study finds.

This structure, called the rete ovarii, was first discovered in humans over a century ago, but until now, it was considered a so-called vestigial structure — not crucial in adult female anatomy, but a leftover from fetal development. Vestigial anatomical structures, or "vestiges," are generally thought to have once had a crucial function that was later lost in the course of human evolution.

But according to a new study, published March 19 in the journal eLife, the rete ovarii (RO) may actually play an important role in ovarian function, and therefore, fertility. The work also showed that the structure has three distinct regions and may respond to hormonal signals.

"The female reproductive tract is often thought to consist of the vulva, vagina, cervix, uterus, oviduct, and ovaries," the researchers wrote in their paper. "We suggest that the RO be added to this list and investigated as an additional component of female reproductive function."

Although their study is based in mice, the researchers think it likely applies to people because the structure is also present in a number of other mammal species, including cows, cats, sheep, pigs, dogs and monkeys. Additionally, humans and mice share similar early sex-organ development pathways, so the scientists assume that the structure and its developmental cues might be similar in humans.

Related: 10 body parts that are useless in humans (or maybe not)

The RO is a horseshoe-shaped network of tubes nestled beneath the ovary, at the site where blood vessels and nerves enter the organ. However, despite the structure being highly conserved among mammals, when it was first found in humans in 1870, scientists deemed it to have no use.

"When this structure was first discovered in the late 1800s it was assumed that it had no purpose because scientists couldn't see its function within the body," Adam Taylor, a professor of anatomy at Lancaster University who was not involved with the recent study, told Live Science in an email.

At the time, "scientists also didn't have the same imaging, microscopic and molecular techniques available today," Taylor added. "These enable us to detect changes in blood flow, size changes of internal structures during life or ability to detect the proteins produced by the rete ovarii and compare these to similar ones produced elsewhere in the body where the function is known."

Now, in the new paper, researchers have applied modern methods to grant new insight into the RO. Some of their experiments used living mice, so that the researchers could study how the RO develops in the womb. Other tissues analyzed in the study were collected from euthanized animals after death.

The study found that the RO contains three distinct regions that mature during fetal development and then are maintained in adulthood. These regions include the intraovarian rete (IOR), located within the ovary itself; the extraovarian rete (EOR), made of convoluted tubules that join up into a bulb at one end; and the connecting rete (CR), a transitional zone between the IOR and EOR.

Using mass spectrometry — a technique used to identify and quantify molecules — the researchers discovered that, at birth, the EOR contains thousands of proteins within its tubes that its own cells appear to produce. One protein was insulin-like growth factor-binding protein 2 (IGFBP2), may be involved in ovary function. The protein may modulate the availability and activity of insulin-like growth factors (IGFs), which are structurally similar to insulin and important for the development of the follicles that carry immature eggs and hormones in the ovary.

In other experiments, the researchers watched fluorescent dye move through the EOR, revealing that fluid within the EOR is propelled toward the ovary. This further suggests that the RO has a role in ovarian function.

In another analysis, they found that the cells of the RO expressed, or switched on, genes that code for a variety of hormone receptors, including receptors for the sex hormones estrogen and progesterone. These hormones play important roles in female reproduction and health, helping to orchestrate the menstrual cycle, among other jobs.

"It appears that the rete ovarii may have a role in ovarian homeostasis - maintaining the ovaries and their environment," Taylor suggested. "Similarly they appear to be able to detect fluid movement in and around the ovaries and their microenvironment. Finally and most interestingly is the potential endocrine [hormonal] role that the rete ovarii may have."

The researchers behind the study suggest that the EOR may "act as an antenna" to receive signals from the rest of the body, both via hormones and nerves, and then send that information on to the ovary via the proteins it secretes and transports.

"There's still so much we can't even begin to comprehend about female anatomy," study lead author Dilara Anbarci, a developmental biologist at the University of Michigan, told Science News. "I hope this encourages more investigation in reevaluating what we don't already know about the ovary."

The researchers hope to further investigate the function and component structures of the rete ovarii, looking into how the EOR actually responds to hormones and whether the proteins it secretes change in response to changes in the body.

This research challenges the traditional view of the RO being considered redundant, proposing instead that it has a secret wealth of functions. Figuring out how the rete ovarii works could one day help scientists better understand and treat conditions of the female reproductive system.

"The endocrine system plays a key role in gynaecological health," Taylor said. "A greater understanding of any structures in this region has the potential to open up new therapeutic avenues and opportunities in treating various conditions."

In a world first, a baby has been born after being conceived through an IVF procedure largely completed by remotely operated robots.

This milestone serves as a proof-of-concept, standardizing a complex, precise fertilization procedure. The scientists behind the work say it could increase the success rate of one type of IVF in the future.

The embryo was created using a process called intracytoplasmic sperm injection (ICSI), a type of in-vitro fertilization (IVF) that has existed since the 1990s. In conventional IVF, an egg cell is placed in a dish amidst thousands of sperm, whereas ICSI involves injecting one sperm cell directly into an egg. The latter method is useful in the case of male infertility, in which the sperm may have trouble reaching the egg without intervention.

Now, a paper published Thursday (April 10) in the journal Reproductive BioMedicine Online, details a way of automating ICSI.

Related: IVF may raise risk of certain disorders in babies — and epigenetic 'signatures' in the placenta could explain why

Why automate IVF?

In the study, the procedure was performed entirely by machines in Guadalajara, Mexico, while embryologists and engineers in Hudson, New York, monitored the process, initiating each step remotely. This resulted in an embryo that then successfully implanted in a woman's womb, enabling the 40-year-old patient to carry a pregnancy to term.

The technology automating the process was developed by a team at Conceivable Life Sciences, a fertility biotech company headquartered in New York City. The team designed a system that can complete the 23 steps involved in ICSI, from selecting the optimal sperm to injecting it into an egg to choosing the most viable embryos. The system does not automate the sperm or egg collection process, nor the process of introducing the embryo to the womb.

"We have created a platform that has for the first time ever standardized ICSI," the paper's co-author Alejandro Chavez-Badiola, co-founder and Chief Medical Officer of Conceivable, told Live Science. Standardization can help reduce human error in ICSI and thus reduce the chance of egg degeneration during the procedure, Chavez-Badiola said.

"Performing ICSI for hundreds of eggs in a single day is an arduous task,” noted Dr. Erkan Buyuk, a reproductive endocrinologist and infertility specialist at RMA of New York, who wasn't involved in the research.

"Any technologic innovation that would cut down on this effort would be much appreciated in any embryology lab," Buyuk, who is also a clinical professor at the Icahn School of Medicine at Mount Sinai, told Live Science in an email.

ICSI involves selecting a sperm, immobilizing it, picking it up, and injecting it into the egg. "Everyone has their own technique" when it comes to performing this process, Chavez-Badiola said, but egg cells are very delicate and at risk of degenerating during ICSI.

Automating ICSI could reduce this degeneration by reducing mechanical resistance against the membrane of the egg — too much tension during injection can compromise fertilization or destroy the egg entirely, according to the paper.

Related: Do sperm really race to the egg?

How the automated system works

Conceivable's automated system uses an artificial intelligence (AI) algorithm to select optimal sperm to inject into the egg, based on the sperm cells' shape. A second AI algorithm then identifies the most viable embryos, assessing the appearance of their chromosomes and their potential to implant in the uterine wall.

A laser is used to immobilize sperm tails precisely at the midpoint, and a motor then pierces the egg's membrane with a single movement to inject the sperm cell. Each step of the process is initiated by a person pushing a button as they monitor the procedure unfolding.

The penetration of the sperm into the egg doesn't guarantee fertilization in either conventional IVF or ICSI, but it is, of course, a key step. From there, the fertilized egg is introduced to the uterus by a doctor and must implant to result in pregnancy.

The paper notes that this automated ICSI process takes more time compared to the manual process. It took the automated system, on average, 9 minutes and 56 seconds per egg, while the manual process clocked in at 1 minute and 22 seconds on average, per egg.

The team used a total of eight egg cells in this experiment. Five were fertilized through the new process, while three were fertilized through manual ICSI. The automated system produced four embryos from the five eggs, while all three eggs in the manual group were successfully fertilized.

Next steps

Chavez-Badiola noted that the team is continuing to improve upon the automated system.

Buyuk also emphasized that this trial marks a starting point. "Multiple studies are needed to ensure safety and efficacy of the procedure, ensuring the sperm with the highest reproductive capacity is selected while damage to the oocyte [egg cell] is minimized," he said.

Nonetheless, Buyuk and others in the field recognize the technological advance as important.

"Experienced, manual work in the embryology laboratory is a rate-limiting step in the IVF laboratory," said Dr. Emily Jungheim, chief of reproductive endocrinology and infertility at Northwestern Medicine Center for Fertility and Reproductive Medicine, told Live Science in an email. "If done right, the tools described in the paper could improve access to and scalability of IVF," said Jungheim, who was not involved in the work.

Chavez-Badiola says the "ultimate goal" is to achieve "end-to-end automation" of ICSI — however, a human will always be part of the process. For instance, embryologists would oversee the process to ensure every step goes as planned, while engineers ensure the equipment functions properly. Ideally, this innovation will "bring down the costs, improve access, and allow for more families to have the joy of children," Chavez-Badiola said.

"It's so exciting," he said. "We're making history."

Editor's note: This story was updated at 6:45 p.m. on April 14, 2025, to clarify that this is the first baby born via a remotely operated, automated ICSI procedure. The article was first published earlier the same day. Dr. Erkan Buyuk's title was also updated.

This article is for informational purposes only and is not meant to offer medical advice.

In the United States, an estimated 645,000 men ages 20 to 50 have azoospermia, a condition in which no sperm are present in their ejaculate. Now, scientists are testing a potential treatment: transplanting sperm-forming stem cells into the reproductive system.

"If refined and proven safe, spermatogonial stem cell (SSC) transplantation could be a revolutionary fertility-restoring technique for men who've lost the ability to produce sperm," Dr. Justin Houman, an assistant professor of urology at Cedars-Sinai Medical Center who was not involved in the study, told Live Science in an email.

It could be especially helpful for "cancer survivors treated before puberty or men with genetic or acquired testicular failure," he added.

So what does this experimental treatment involve?

Related: Sperm cells carry traces of childhood stress, epigenetic study finds

Sperm-forming stem cells are at the core of the therapy. These cells, found in the testicles even before puberty, typically mature into sperm when testosterone levels rise during adolescence.

But medical conditions — like a blockage in the reproductive tract or certain genetic mutations or hormonal problems — and treatments such as chemotherapy can damage these stem cells or block their development into sperm, thus leading to infertility.

If a young patient wishes to preserve their sperm-forming stem cells for future use, doctors can use an ultrasound-guided needle to collect the stem cells into the rete testis — a network of small tubes that connects to the seminiferous tubules, where sperm are typically produced. The needle is carefully inserted into these tubes through the base of the scrotum, and once collected, the stem cells are frozen.

Later on, doctors can then reintroduce the preserved stem cells into the rete testis, using a similar, ultrasound-guided technique. The goal is for the cells to implant in the seminiferous tubules, where they can mature and begin producing sperm, mimicking the natural process that occurs during puberty.

This procedure has previously been tested in animals, and it successfully enabled male mice and monkeys to produce sperm and father offspring.

Now, researchers have documented the technique's first use in humans. According to a paper published March 26 on preprint server medRxiv, a man in his early 20s has now received a transplant of his own, once-frozen stem cells. He had his sperm-forming stem cells preserved as a child, before he underwent chemotherapy for bone cancer.

If the stem-cell transplant is successful, the man's body should begin producing sperm, which was not possible before the procedure due to azoospermia. So far, ultrasounds have confirmed that the transplantation procedure didn't damage the patient's testicular tissue, and his hormone levels are normal.

No sperm have been detected in his semen yet, but the researchers are continuing to analyze his semen twice a year to see if the reproductive cells show up.

One possible reason for the lack of detectable sperm, according to the researchers, is that only a small quantity of stem cells were collected in the patient's childhood, to minimize harm to his tissues. That means the number of preserved and transplanted cells capable of developing into sperm remains low. As a result, sperm production may be limited.

Related: 100 million-year-old sperm is the oldest ever found. And it's giant.

If sperm do not ever appear in the patient's ejaculate but the patient wants to father children, doctors could attempt to recover, via surgery, any small amount of sperm made by the stem cells.

Dr. Laura Gemmell, a reproductive and endocrinology fellow at the Columbia University Fertility Center, suggested another alternative: a technique called the Sperm Tracking and Recovery (STAR) System. This is a machine developed at the Columbia University Fertility Center that combines artificial intelligence technology, robotics, and microfluidics, a technology that uses tiny channels to analyze fluid within a device. This tech identifies and recovers extremely scarce sperm cells from an ejaculate, she told Live Science in an email.

It takes only one sperm to conceive a child, Gemmel noted. "If we can find that sperm noninvasively, we can inject that single sperm into an egg and make an embryo," Gemmel said.

She added that, "our field has seen success with ovarian cryopreservation and retransplantation in young girls with childhood cancers. I'm hopeful that in the future, we can provide an option for young boys who want to one day father a biologic child."

As with all medical procedures, sperm stem cell transplants come with some risks.

For example, there's a chance that a fraction of the transplanted stem cells have cancer-causing genetic mutations and could someday develop into a tumor, especially in patients who've had leukemia in the past, Houman said. And even though the procedure uses the patient's own cells, there's a "theoretical risk" that the immune system could still react and trigger inflammation, he said.

There are also ethical concerns around freezing the sperm stem cells from young boys — namely, how can doctors be sure the children can fully consent to the procedure, and that they have clear expectations around the long-term storage of their cells?

"We need to proceed cautiously, and with rigorous oversight," he said. "This is promising science — but it's still early days."

Editor's note: This story was updated on April 7, 2025, to correct the spelling of Dr. Laura Gemmell's name.

This article is for informational purposes only and is not meant to offer medical advice.

Oxytocin, the "cuddle hormone" that's known for its involvement in bonding, may also play a role in putting early pregnancies on pause, a study of lab animals finds.

New research in mice shows that the hormone can put embryos in the earliest stages of development into a kind of hibernation state. Once triggered, this process, called "diapause," might allow a mouse mother to delay a pregnancy at a time when resources are scarce — such as while she is still nursing a previous litter of newborn mouse pups.

"The fact that oxytocin had an influence on this was a little bit of a surprise," study co-author Moses Chao, a neuroscientist at the New York University Grossman School of Medicine, told Live Science.

Diapause, in general, is a bit of a mystery. The phenomenon naturally occurs in marsupials, such as kangaroos and possums, and in at least 130 species of mammals, including mice and bats.

It might even occur in humans — it's a difficult phenomenon to track in most human pregnancies, but a few scattered reports from in vitro fertilization (IVF) clinics suggest that, in rare cases, embryos transferred into the uterus might hang out for weeks before actually implanting in the organ. In one case reported in 1996, it took five weeks after embryo transfer for the pregnancy to begin.

Related: Pregnancy may speed up 'biological aging,' study suggests

It's not clear how long diapause can last, Chao said, nor is much known about how embryos enter this state of suspended animation.

Study first author Jessica Minder, a graduate student at the NYU Grossman School of Medicine, was interested in oxytocin's role in diapause because the hormone is also known to be involved in embryonic development and nursing in mammals, including humans.

Minder and colleagues began the work by introducing male mice into the enclosures of female mice that had just given birth, allowing the rodents to mate while the females were still nursing their first litters. The researchers found that the resulting pregnancies lasted about a week longer in still-nursing female mice than they did in mice that were not nursing.

They think this likely reflects a pre-implantation "pause." As mouse pregnancies typically last only 19 to 21 days, the pause reflects a significant delay in the process.

The team then set about exploring how this pause might occur.

In another group of newly pregnant mice, the team used a technique called optogenetics, which uses light to switch on specific neurons, to make the brains of the mouse moms release oxytocin. The researchers timed this stimulation to mimic the pulses of oxytocin seen during nursing.

After five days of this treatment, they removed the mice's uteruses to assess embryonic development. Five of the six mouse mothers had embryos that underwent diapause, as evidenced by a lack of development.

Meanwhile, in a comparison group, pregnant mice who did not have their oxytocin stimulated did not show any signs of diapause.

In another experiment, the team treated early mouse embryos with oxytocin in lab dishes, and that also induced cellular changes consistent with diapause.

Together, the evidence suggested that oxytocin caused embryonic cells to slow their translation of genes into proteins, the researchers reported March 5 in the journal Science Advances. This multistep process involves copying down instructions from DNA into a new molecule, called RNA, that gets shipped to a cell's protein construction sites.

Embryos without oxytocin receptors can still undergo diapause, Chao noted, so there are probably multiple signals that can trigger the pause. However, oxytocin seems to be important for the embryos to survive this arrest.

When the researchers turned off oxytocin receptors in the mouse embryos, they found that only 11% survived diapause, compared with 42% of the embryos with working oxytocin receptors.

This research is an early exploration of the metabolism of early embryos, Chao said. Eventually, a better understanding of these mechanisms might reveal insight into why early miscarriages happen in people and could possibly lead to new fertility treatments.

More work will be needed to understand the biochemical steps that lead from oxytocin stimulation to diapause, Chao said.

The new findings could also be helpful for understanding cell survival more generally, Chao added. For example, half of the nerve cells in the early embryo die as the developing nervous system is refined before birth. However, many of the nerve cells that develop in the womb ultimately last a lifetime.

"Later on [in development], you don't want half your cells dying," Chao said, "so we're very interested in what keeps those cells going."

An enzyme made famous by the COVID-19 pandemic plays an unsung role in healthy placenta development during pregnancy, according to a new study.

The enzyme, called angiotensin-converting enzyme 2 (ACE2), can be exploited by the novel coronavirus as a doorway into human cells. However, outside the context of COVID, ACE2 plays important roles in human health — including during pregnancy.

Broadly, ACE2 is part of a system that helps regulate blood pressure and fluid levels in the body. In this system, ACE2 helps widen blood vessels and triggers anti-inflammatory responses while its counterpart, angiotensin-converting enzyme (ACE), boosts cell and tissue growth.

In past studies, different versions of the ACE2 gene have been tied to pregnancy complications, such as preeclampsia, which can cause high blood pressure and liver and kidney problems during or after pregnancy, as well as babies being small for their gestational age.

These problems have also been tied to issues with the placenta, which provides oxygen and nutrients to the fetus, but the role ACE2 plays in the placenta hadn't yet been clarified.

Now, in a new study, scientists found that tweaking the gene for ACE2, or knocking it out entirely, causes lab-grown models of the placenta to end up smaller and less symmetrical. The findings, reported Feb. 7 in the journal Cell Death and Disease, shed light on the role of ACE2 in pregnancy and could help scientists develop treatments for complications related to the gene and its activity.

Related: 'Zombie cells' in the placenta may cause heart failure in pregnancy

"By having [a specific variant in the ACE2 gene], you're 23 times more likely to have a small-for-gestational-age baby," study coauthor Anya Arthurs, a molecular biologist at Flinders University in Australia, told Live Science. "I'd seen this statistic, but no one had actually looked at why that happened."

Arthurs and her colleagues used stem cells collected from donated placental tissue to grow organoids — small, simplified versions of placentas that can be grown in lab dishes. They grew some organoids with the normal ACE2 gene and others without it; plus, they edited a third group to swap one building block in the gene for out for another at a key site. In this way, they made the third group of miniature placentas carry the ACE2 variant that's known to be associated with small-for-gestational-age babies.

These edits to the genome enabled the team to study how changes to the ACE2 gene would affect placental development.

Both the organoids that lacked the ACE2 gene and the ones with the edited gene grew more slowly and were less symmetrical than the organoids with the normal gene, the scientists found. The ratio of ACE2 to ACE proteins was also higher in the edited organoids than in the normal organoids, while the ones that lacked the ACE2 gene didn't produce any ACE2 proteins at all.

Together, these results suggest that disrupting the typical ratio of these key proteins could somehow affect placenta growth and development for the worse.

"It's really important that these two sides of the system exist in a balance in a tissue," Arthurs said. "If you have only one, you're going to have problems — too invasive, too inflammatory." With too much ACE, cells might grow out of control like they do in cancer.

"And if you have too much of this ACE2 anti-inflammatory, anti-proliferative pathway, you're not going to have a successful pregnancy because the placenta is not going to be able to form the way it should," Arthurs suggested.

The study is the first to explore gene editing in a human placental organoid as a way to investigate the molecular causes of pregnancy disorders. Researchers could use the technique to study other pregnancy complications, such as gestational hypertension, said Gloria Valdés, a researcher at the Pontifical Catholic University of Chile, who was not involved in the research.

"The field that the paper has opened is extremely interesting," Valdes told Live Science.

Arthurs is now studying placental organoids that mimic a preeclamptic placenta, which releases molecules that can go on to affect kidney and liver function. Better understanding the placenta's role in the disease could point to potential treatments.

"I think it's important to know the molecular mechanisms which underpin a pathology," Arthurs said. "If you don't know the molecular mechanism, you can't design a therapy."

The patient: A 15-year-old girl in Lesotho, Southern Africa

The symptoms: In 1988, a teen visited the hospital with intermittent and acute abdominal pain. An examination revealed that she was about nine months pregnant — but she said she had been unaware of the pregnancy. Her uterus was contracting at regular intervals and the fetus was oriented with its head downward in the birth canal.

What happened next: When emergency room doctors inspected the patient's vulva, they found no vaginal opening. Instead, there was a skin-covered shallow indentation between her labia minora — the vulva's inner lips — and below her urethral meatus, the external opening of the urethra that transports urine out of the bladder. This rare condition, in which the vaginal opening is absent or closed, is known as distal vaginal atresia and affects an estimated 1 in 4,000 to 10,000 newborn females.

Doctors gave the patient spinal anaesthesia and performed an emergency cesarean section (C-section), delivering a healthy baby boy weighing 6.2 pounds (2.8 kilograms), according to a report of the case.

Examination of the patient after her delivery revealed that her uterus terminated in a vagina that was just 0.8 inches (2 centimeters) deep, according to the case report. (Vaginal depth is typically 2 to 4 inches (5 to 10 cm) but can extend up to 8 inches (20 cm) during arousal.)

The diagnosis: The patient had previously visited the same emergency room 278 days, or just over nine months, earlier, after a man stabbed her in the upper abdomen. The knife had penetrated her abdominal wall and created two wounds in her stomach. At the time, doctors treated her injuries and discharged her from the hospital.

Months later, as the patient was recovering from the cesarean operation, she told a nurse that the attack occurred when an ex-lover had found her fellating her new boyfriend. The doctors concluded that, after the patient was stabbed, sperm she had swallowed migrated to her reproductive organs through the tears in her digestive tract, thus causing her pregnancy.

The treatment: The patient's recovery was uneventful, and she and her boyfriend ultimately accepted the circumstances of the child's conception, the report added. A few years later, the boy visibly resembled his father — the man she had been fellating at the time of the attack — a fact that "excludes an even more miraculous conception," the emergency room physician wrote.

What makes the case unique: Fertilization typically occurs after sperm is introduced to the female reproductive system through the vagina. Environments that are highly acidic, such as the gastrointestinal tract, are inhospitable to sperm. However, saliva is lower in acid than other parts of the digestive system.

Acidity is measured by the pH scale, which runs from 0 to 14 — the lower the number, the more acid is present. The stomach is acidic, with a pH of 1.5 to 3.5. Saliva typically has a pH of 6.7, on average, which is close to neutral. This could explain why the sperm in this case was still viable after being swallowed, according to the report.

What's more, when people are malnourished, the digestive system becomes less acidic and more alkaline, the doctor wrote. The patient was underfed at the time of the knifing, which may have provided a more hospitable environment for the swallowed sperm as it traveled from her digestive system and passed through the knife wounds in her stomach to enter her uterus, the doctor theorized in the report.

This article is for informational purposes only and is not meant to offer medical advice.