The fragile and battered remains of an infant who lived about 6,000 years in Mesopotamia may be the oldest documented case of child abuse from the Middle East and one of the oldest known cases of its kind in the world, a new study finds.

Researchers unearthed the infant's remains in Syria, but at the time the infant died, sometime between 4200 and 3900 B.C., it was buried in Tell Brak, one of the world's earliest cities. It's possible that the difficulties associated with early urbanization played a role in the child's abuse, the researchers noted.

The team determined that, based on the infant's tooth development, the child was 6 to 9 months old at death. An analysis of the remains, which were interred in a children's burial ground within a Late Copper Age workshop district, revealed that the infant had four fractured ribs near the breastbone. The right thigh bone had abnormal growth, while both sides of the skull bore active, porous lesions. These injuries point to the bones being subject to intense and repetitive external forces, and the nature of the lesions don't fit easily with an accidental fall, the researchers said.

"Ribs shouldn't break" in such a small child, study co-author Aleksandra Grzegorska, a bioarchaeologist at the University of Warsaw, told Live Science. Although rib fractures are relatively common in adults, they suggest child abuse in young infants, she said.

In the study, published May 21 in the International Journal of Osteoarchaeology, Grzegorska and her colleagues systematically ruled out other explanations for the injuries, including rickets, scurvy, birth trauma and violent coughing from illnesses such as tuberculosis. Vitamin deficiencies were unlikely, the researchers noted, given that ancient Mesopotamia had ample sunlight and fresh produce due to the fertile land between the two rivers. Birth-related fractures typically heal within weeks in infants, and bone density and growth measurements for the baby matched those of its peers from that time, indicating that the child didn't have an underlying skeletal condition.

To gauge how unusual the injuries were, the team compared the infant to other children excavated from the same burial area. None of the other youngsters with substantial rib preservation showed similar fractures, making the infant's injuries an outlier in the local population.

It appears that the infant likely experienced "caregiver-induced violence," Grzegorska said. This term is used because the evidence can't identify who caused the harm or confirm intent, Grzegorska said. "We don't want to point fingers at any specific individual," she said, noting that in many ancient cultures, multiple family members, not just parents, helped raise children.

Other clues that might shed light on the infant's injuries are missing from this case, she added. Unlike modern clinicians, bioarchaeologists can't interview a living patient or bystander, or examine soft tissue that might reveal more about the abuse. The partially healed state of the fractures suggest the infant survived for some time after the injuries were inflicted, Grzegorska found — an indication that the trauma was not immediately fatal.

Around the time the infant died, Tell Brak was transforming into a city, so the authors suggested that the stresses of early urbanization and possibly less support from extended kin could have contributed to the violence. Centuries after the infant died, upheavals related to city building appear to have led to mass deaths that were likely caused by violent conflict, Grzegorska noted.

Documented cases of child abuse remain exceptionally rare in the archaeological record, with only a handful previously identified in places such as Egypt, France and Lithuania.

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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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.

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.

Compared with other animals, human babies start out with a lot to learn. Whereas some animals walk within hours of being born or hatching, human babies take months or years to master even the most basic functions. If you've ever had a baby and a pet at the same time, you might have wondered which one is smarter.

So what does science say about how the intelligence of human children compares with that of our fur babies? It's a complex question, and the answer depends on the dimension of intelligence, the animal, and the person you ask.

How smart are dogs compared with babies?

Stanley Coren, a professor emeritus of psychology at the University of British Columbia, has spent his career investigating dog intelligence. He adapted a psychological measure called mental age to test dogs' cognitive abilities.

While it's not possible to draw an exact comparison between dog and human intelligence, Coren said dogs do have some cognitive skills, such as vocabulary and counting, that roughly correspond to those of young toddlers. For example, the average dog can understand about 165 words and signals. In exceptional cases, some dogs can learn significantly more. For example, Chaser the border collie, who was specially trained by a retired psychology professor, was reported to understand over 1,000 words.

Most dogs can also "count" up to three, Coren said. If the idea of a dog being able to count sounds unlikely to you, try this: Show your dog three treats, hide them all in your hand, and then give the dog only two. Most dogs will know one treat is still missing and nuzzle your hand to try finding it. And in the lab, studies show that dogs' brains light up similarly to humans' as they see the number of dots on a screen change, suggesting they recognize when a quantity goes up or down.

Coren added that trained retrievers, which are bred to fetch downed birds or other game, often keep track of five or more objects in order while hunting. So, even though dogs can't recite "one, two, three," like a preschooler might, these sorts of behaviors show that many dogs have some intrinsic understanding of basic counting. In comparison, research shows that 14- and 18-month old human infants are already able to distinguish between two and four objects when an adult counts them.

By analyzing these sorts of cognitive functions, you can estimate the "mental age" of dogs on a human scale, Coren said. "We basically found out that the average dog has a mental age which is about the equivalent of a 2-and-a-half-year-old child," at least when it comes to certain cognitive skills such as vocabulary, counting and emotional awareness, he told Live Science. He said for different dogs, the number can range from about age 2 to 3.

Related: Are dogs smarter than wolves?

Keeping that mental age in mind can help dog owners understand their dogs' capabilities, Coren said. For example, just as 2-year-olds aren't yet fully capable of experiencing and comprehending guilt, dogs aren't, either; the shy behavior exhibited by dogs after misbehaving is actually just the fear of punishment, Coren said.

It's important to note that dogs' intelligence is highly dependent on their breed, experience and training. For example, border collies and poodles generally rank as more intelligent than Chihuahuas and bulldogs. There's also the caveat that these tests don't account for different breeds' unique, instinctive skills, such as herding or scent tracking, which are their own forms of intelligence but are difficult to compare to human cognition.

"Dogs are not four-footed people in fur coats," Coren said.

How smart are cats versus babies?

The research on domestic cat intelligence is less plentiful, but some studies have probed the cognitive abilities of cats. "We might look at things like problem-solving or innovation/behavioral flexibility as kind of a substitute for an intelligence test," Jennifer Vonk, a professor of psychology at Oakland University in Michigan, told Live Science in an email.

The landmark research on cat intelligence, conducted by Edward Thorndike in 1898, examined cats' ability to free themselves from a box by pulling a door open. Although the cats were able to open the door only through trial and error at first, the time it took them to escape the boxes generally decreased as Thorndike repeated the trials, showing that the cats were able to learn. Subsequent studies that used treats in puzzle boxes found that cats could learn new solutions when the puzzle box changed, which demonstrated cats' ability to adapt flexibly to new learning environments, Vonk said. And while it would be unethical to put human babies in a puzzle box, kids can begin escaping cribs as young as 16 months of age.

Other research has evaluated cats' memory, which is another important dimension of cognition. Studies have found that cats strategically search for food based on just a single memory, for example. Studies also show that cats grasp the concept of object permanence — the understanding that an object still exists even if it is no longer visible. Human babies usually learn object permanence between 4 and 10 months of age. And a recent study found that cats may even be better at associating words with pictures than human toddlers are.

But even though it's possible to quantify aspects of cat intelligence with these tests, Vonk doesn't think it makes sense to view cat intelligence through the lens of human development.

"I don't think it is relevant to compare animal abilities to those of human children because other species are not just developmentally delayed humans," she said. "They have evolved to solve different problems because they evolved in different ecological contexts and live in different environments."

These different evolutionary pressures have made cats excel at skills such as hunting and differentiating scents. "They are probably far more efficient hunters than most humans will ever be," Vonk said.

Ultimately, cats' unique adaptations also mean they simply may not be motivated to perform well on intelligence measures the way humans are. Over history, human survival has been dependent on tasks such as tool building and language development. Other animals haven't had the same evolutionary pressures — for example, cats rely on their sense of smell and physical coordination to hunt, rather than their ability to communicate or build tools — so Vonk believes it just doesn't work to compare cats with young humans.

"I think you cannot think about animals as being comparable to humans at different stages of development," Vonk said. "That's a comparison I try very hard to never make. We have to think about what abilities make sense for cats to have and understand why cats do well at the things they do well at, and worry less about comparing them to humans."

A new RSV drug designed to protect young children was 93% effective at preventing hospitalization for the viral disease, a new study reports. Furthermore, the drug was 89% effective at preventing all types of doctor visits for RSV, which is short for "respiratory syncytial virus."

The new research, published Monday (Dec. 9) in the journal JAMA Pediatrics, focused on nirsevimab (Beyfortus), a drug approved in 2023. The medicine, which is given as an injection, uses lab-made antibodies to block RSV from getting into cells. Unlike a vaccine, nirsevimab doesn't teach the body to make its own antibodies; rather, it provides a ready-made supply.

The new study's results suggest that nirsevimab is very effective at protecting young children from needing hospitalization for RSV, as well as other lesser degrees of medical care, such as outpatient visits. However, "only a small fraction" of infants in the study who were eligible for the drug actually got nirsevimab, the study authors noted.

Ultimately, the findings suggest that nirsevimab could have a "substantial public health impact" in future RSV seasons if the drug were used more widely, they concluded.

Related: Who should get the new RSV vaccines? Here's everything you need to know

Before nirsevimab's approval in 2023, there were no widespread strategies for preventing RSV in infants, for whom the virus is the leading cause of hospitalization.

Each year in the United States, 2 to 3 out of every 100 infants under 6 months old are hospitalized for RSV, according to the Centers for Disease Control and Prevention (CDC). These cases start off mild, causing a runny nose and cough, but then progress to trigger inflammation and infection in the lungs. Children hospitalized for RSV often need supplemental oxygen and IV fluids, as well as breathing support from a ventilator.

To see how well nirsevimab is working in the real world, the study's authors compared three RSV seasons before the drug's approval to the 2023-2024 season, after its approval. The three pre-approval seasons spanned 2017 to 2020, before the COVID-19 pandemic, which disrupted typical patterns of RSV spread.

The drug is currently recommended for all babies younger than 8 months old whose mothers haven't gotten the maternal vaccine against RSV. (If a person gets the vaccine during pregnancy, the resulting antibodies pass to the fetus before birth.)

The CDC recommends that eligible babies get nirsevimab just before the start of their first RSV season — around October — or within a week of birth, if they're born between October and March. Select older children are also recommended to get the drug before their second RSV season.

In all, the new study included data from nearly 28,700 children under age 5 who required medical care for a respiratory infection during RSV season. The children had been treated at seven academic pediatric medical centers, and they needed different levels of care, ranging from outpatient doctor visits to hospitalization.

Of the children, roughly 7,500 were treated for RSV, and 4,500 of those kids were hospitalized for the infection. The remaining children, who had tested negative for RSV, served as a point of comparison for the study's analyses.

The study found that RSV accounted for a similar proportion of respiratory-infection-related medical visits before and after nirsevimab's approval. Looking at the 2023-2024 season, the researchers found that the number of infants who got nirsevimab was small: 402 got the new drug, while 16 got an older drug called palivizumab (Synagis) that's recommended only for certain kids.

"Only a small fraction of infants in their first RSV season had received nirsevimab," the authors wrote.

An additional 70 infants were born to mothers who'd gotten the maternal RSV vaccine. The researchers had planned to study the vaccine's real-world effectiveness as well, but they said they would have needed more data to do so.

There are a number of reasons that uptake of both nirsevimab and the vaccine might have been low in 2023, the authors noted. There were supply issues with nirsevimab during the 2023-2024 season, for example. In addition, RSV season kicked off unusually early in 2023, and the maternal vaccine didn't become available until around the same time.

Despite the study's limitations, the research and other work collectively suggest that nirsevimab has the potential to substantially reduce infant RSV hospitalizations — if and when it's used more widely.

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

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Cats perform better than toddlers on a simple measure of language comprehension. The research, published Oct. 4 in the journal Scientific Reports, revealed that cats form associations between pictures and words around four times faster than human toddlers do.

Language is the most important tool humans use to communicate. But the ability to comprehend speech is not unique to Homo sapiens. Some apes associate spoken words with written symbols or pictures, while African gray parrots can understand and respond to spoken instructions. Dogs, meanwhile, have been trained to understand and respond to simple vocabulary.

However, we know far less about humans' other major companion, cats. "Cats can definitely recognize the sound of words coming from people, and more and more studies prove that cats rely on interaction with humans in problem-solving," Dr. Carlo Siracusa, a veterinary behaviorist at the University of Pennsylvania, told Live Science. There is even limited evidence that cats can respond to pointing, and research in the past five years has shown that cats can recognize not only their own names but also those of familiar humans and animals. But can they associate words and objects more generally?

Related: Over 40% of pet cats play fetch — but scientists aren't quite sure why

To test this theory, Saho Takagi and her team at Azabu University in Japan gave 31 adult cats a simple word game used to investigate the same ability in babies. The cats were shown two nine-second cartoon clips with recordings of their owners repeating a made-up word over each image. The sequence of clips — a red sun labeled "paramo" and a blue unicorn with the word "keraru" — was repeated until the cats appeared to get bored and paid 50% less attention to the screen.

After a short break, the image clips were repeated, but this time, half of the pairings were inverted. The switched clips visibly confused the cats, with recordings of "paramo" alongside the unicorn and "keraru" with the sun holding feline interest an average of 15% longer. That the cats noticed this change and were clearly perplexed by it is good evidence that they had formed a link between the words and images, Takagi and colleagues wrote in the study.

"Some cats even gazed at the screen with their pupils dilated during the 'switched' condition," Takagi told Science magazine. "It was cute to see how seriously they participated in the experiment."

The experiment revealed that the cats were able to learn the combinations from just two nine-second exposures — significantly faster than toddlers, who required at least four 20-second trials.

However, these comparisons should not be overinterpreted. "You're comparing an adult animal with an immature animal from a different species," Siracusa told Live Science. "In addition, we humans are interpreting the behavior of a completely different species. When we interpret children's behavior, we are interpreting the behavior of our same species, which we are programmed by natural selection to perceive in an innate way."

Comparison with other domestic species, such as dogs, is possibly more useful, Siracusa said. But it's still vital to consider their key evolutionary differences, he added. Siracusa said the research team developed a reasonable and effective method to study the question, especially given the difficulty of studying cats.

However, by their very nature, cognitive studies have limitations that are important to bear in mind when interpreting the results. "A certain number of the cats have to be excluded, so there's already a bias —not a fault of the research," he said. "It's just difficult to engage animals." Despite its limitations, the study does show that cats are capable of forming picture-word associations, the team wrote in the paper, although whether this is an innate ability or a product of domestication remains a mystery.

There are millions of animal species on our planet, and each has a reproductive strategy that has evolved to match its specific needs. But which species can have the most babies at one time?

"The question ends up getting complex very quickly," Kathleen Cole, an ichthyologist, or fish scientist, at the University of Hawaii at Manoa, told Live Science. "A lot of potential factors can affect the scenario. "

For starters, which animal you crown for most offspring depends on how you quantify offspring. If you define offspring in terms of the number of gametes, or unfertilized egg and sperm, produced at one time, "fishes really have it by a mile," Cole said. It requires less energy to release unfertilized eggs than to lay them after they're fertilized, so animals that spawn, or release unfertilized eggs and sperm in the water, often have more eggs than non-spawners.

The ocean sunfish (Mola mola) was found to have as many as 300 million eggs in its ovaries at one time. However, because the eggs are fertilized outside the female's body, it's impossible to know how many of those eggs become viable offspring; once the eggs are released into the ocean, there's no way to tell which are hers and no way to track every one through fertilization and development into a baby fish. However, although there are no official assessments of the number of sunfish in the ocean, they are listed as a vulnerable species under the IUCN Red List as a result of accidental capture by fisheries, and are considered to be a naturally rare species, so all those 300 million eggs are not turning into baby sunfish.

Related: Which came first: the chicken or the egg?

In terms of fertilized eggs in one go, social insects take the cake. Some ant species, such as African driver ants (Dorylus wilverthi) can lay as many as 3 million to 4 million eggs in about a month — the queen will choose to fertilize some of these eggs and not others depending on how many male and female offspring she wants to have.

Among birds, game species like the gray partridge (Perdix perdix) is among the top egg layers, with up to 22 eggs per clutch. When it comes to live birth, seahorse fathers can give birth to up to 2,000 live young at once, which they incubate and support via a placenta in their pouch. The venomous vipers known as puff adders (Bitis arietans) are a top contender for terrestrial live-bearers. The record-setting female gave live birth to 156 fully developed snakelets from one pregnancy.

"They're like giant sausages," Alex Pyron, an evolutionary biologist at The George Washington University in Washington, D.C., said about puff adder mothers. "They can pack in a lot of babies."

Why do these animals have so many babies, while animals like elephants and whales usually only have one at a time? One of the factors that influences litter size is lifespan. Shorter-lived animals that won't survive to see their offspring grow will typically have more offspring at once. "They can't sit around and crank out babies," Cole said. "They have to make their mark quick."

Species like bats, which have to be lightweight to fly and carry their pups while airborne, can generally care for only one offspring at a time. And animals that look after their young following birth will generally have fewer offspring because of the larger energy and resource investment it takes to raise each one.

Whether an animal lays eggs or gives birth to live young is also a big factor. Live young take a lot more effort to develop, so live-bearers will often have fewer babies. Animals that live in groups, including species like the prolific African driver ant, can have more babies than solitary animals because of the greater protection offered by the group.

There are always, however, examples that defy the trends. Rabbits and mice, after all, are famous for their large litters despite bearing live young, while dung beetles, which are egg -layers, can lay as few as three eggs at a time.

"Changing environmental conditions and changing ecological conditions can cause the selective pressures responsible for these strategies to shift quickly," Pyron told Live Science. "But why evolutionary one-offs like these arise is always sort of a mystery."

For science, volunteers sniffed out odorous chemicals in the armpit sweat of babies and teenagers. Perhaps unsurprisingly, they found that young children smelled like flowers and teens smelled like goats — but now, we know which chemicals are responsible for each of these odors.

Many of us are familiar with babies' sweet scent, but we may wince while catching a whiff of a teen who's skipped out on that day's deodorant. Previous studies have also found that parents prefer the odors of babies to those of teenagers, which may somewhat influence their affection toward their children. Intrigued by the role scent plays in relationships, lead study author Helene Loos, an aroma researcher at Friedrich Alexander University in Germany, aimed to explore how BO changes throughout life.

In the research, published March 21 in the journal Communications Chemistry, Loos and her colleagues provided 18 young children, ages 0 to 3, and 18 teenagers, ages 14 to 18, with T-shirts with cotton pads sewn into the armpits. After the participants wore the tees for one night's sleep, the researchers sampled smelly substances that had soaked into the pads.

Using gas chromatography, a technique that splits up chemicals with different properties, the researchers separated and detected the individual odorants in each BO sample. Then, they asked volunteers to smell and describe each chemical's scent.

Related: Super sensitive to BO? Maybe blame your genes

Forty-two odorants were detected, with both age groups producing most of them, Loos told Live Science. Note that a single odorant can set off many smell sensors in the nose, and combinations of odorants can trigger unique and complex patterns of activity that differ from what one odorant does alone. Nonetheless, the component scents in a given bouquet influence whether it smells bad or good to the sniffer.

"We were not surprised by the overall findings, but it was very interesting to see the rich variety of compounds," Loos said of the odorants detected. Among these, a group of chemicals called aldehydes was the most diverse, giving off "cardboard-like," "deep-fried" and "nutty" aromas, for example.

BO from both age groups also contained carboxylic acids, a class of organic compounds. Some were pleasant, giving off "fruity" or "dried plum-like" notes. Others were less so, smelling "cheesy," "musty" or like "goat." The team diluted each carboxylic acid several times to assess how intensely each one contributed to BO in both groups. The carboxylic acids from teens' armpits retained their scents after more dilutions than did those from young children, suggesting the chemicals might be secreted in higher concentrations after puberty.

The teen BO also harbored two steroids that were absent from the young kids' samples. One smelled like sandalwood, a common fragrance in perfumes. The other smelled like sweat and urinals — parfum de locker room, if you will.

Changes in people's BO between infancy and puberty may be linked to alterations in their skin, including hormonal changes; a shift in its lipid, or fat, makeup; differences in the skin microbiome; or the activation of sweat glands and sebum glands, which exude an oily substance. However, it's still unclear which of these anatomical changes may explain the differences in this study.

Related: Humans can 'smell' each other's emotions — but we don't know how

In studying the participants' self-made body odorants, "we were very careful in considering all kinds of potential contamination," Loos said. They asked the infants' parents and the teens to avoid smelly foods containing spices, onions or garlic, and they provided perfume-free shower gels and unscented detergents. Nonetheless, many odorants picked up in BO samples were also detected in these provided supplies, so it's unclear how much they influenced the findings.

Conscious that odorants in the air might absorb into the cotton pads, the researchers also provided each participant with a second T-shirt to leave in the room, unworn. Most of the 42 odorants were also found in these unworn tees, but it's unclear whether they emanated off the participants or came from another source.

Some chemicals previously linked to BO went undetected in this study, including acetic acid, which gives vinegar its signature scent. This may be explained by the team studying a small, non-diverse cohort, or the fact that techniques differ in their ability to detect different substances.

Loos and colleagues plan to employ other approaches to capture a wider variety of odorants, as well as to explore how BO changes in other age groups, including older people. They also want to study more-intense BO, following exercise or multiple nights of sleep, for instance.

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Parents are taught that when a baby rubs their eyes, it's a telltale sign they're ready for a nap. But why do babies rub their eyes when they're tired? What triggers this behavior, and what purpose does it serve?

"Unfortunately, we can't ask a baby exactly why they're rubbing their eyes," Dr. Rebecca Dudovitz, an associate professor of general pediatrics at the UCLA David Geffen School of Medicine, told Live Science.

"But we do know from human experience that people do tend to rub their eyes when they're tired, and we think it may have to do with just a feeling of discomfort that you get when your eye muscles have been working hard and it's time for a break," Dudovitz said.

The same way your shoulders might need a massage after you sit at a desk all day, the muscles that help your eyes focus feel better after you rub them. Babies spend a lot of their time staring at objects in their environment, and their eyes get tired.

Related: What happens when a baby takes its first breath?

Staring also dries out the eyes — and considering that babies blink only a few times a minute, it shouldn't be surprising that their eyes get dry, too.

"Tears are not just salt water, but mucus near the surface, salt water in the middle, and a layer of oil from the eyelid meibomian glands to prevent evaporation," Dr. Robert W. Arnold, an ophthalmologist at Alaska Children's Eye & Strabismus, told Live Science via email. "Therefore, a healthy tear is a tri-layer. That tri-layer must be renewed and spread over the surface smoothly by blinking."

When we're faced with too much intense visual attention, we don't blink enough. And without enough blinking, that tri-layer can break apart and leave dry patches on the surface of the cornea, the outer, clear part of the eye that covers the iris and pupil. When that happens, eye rubbing may just be a reminder to blink more.

"This is similar to breathing, the rate of which is usually automatic, and sufficient. However, when we are distracted or tired, we may not breathe often, or deep enough," Arnold said. "Therefore, we sigh. Eye rubbing in children may be akin to sighing for eyeball health."

Rubbing your eyes isn't particularly good for you, however. Excessive eye rubbing can lead to vision problems.

One commonly cited reason it feels good to rub your eyes when you're tired is that it reduces blood pressure by stimulating the trigeminal and vagus nerves, which run from the brain to the eyes and from the brain throughout the body, respectively. In some people, this can reduce heart rate by more than 20% in a phenomenon known as the oculocardiac reflex.

But Arnold questions this reasoning. "There is no obvious reason why a kid would feel better with a slow heart rate," he said.

In fact, the oculocardiac reflex can have life-threatening results, including bradycardia — a heart rate below 60 beats per minute — and cardiac arrest.

"We don't think purposeful stimulation of the oculocardiac reflex is a reason for children rubbing the eyes, but it could be a result of excessive rubbing of the eyes," Arnold said.

But most likely, babies rub their eyes for the same reasons adults do: Their eyes are tired and dry, and they're ready for a nap.

Brain infections and inflammation may explain some cases of sudden infant death syndrome (SIDS), a small study hints.

The research pointed to a specific virus, called human parechovirus 3 (HPeV3),as potentially tied to the death of one child in the study; HPeV3 is known to cause both mild respiratory infections and severe nervous-system infections. At this point, the virus can't be definitively confirmed as the child's cause of death, but the study highlights the idea that some SIDS cases may stem from viral infections and that this notion bears further investigation.

"Our findings demonstrate proof of concept that undetected infections may contribute to risk of SIDS and that increased surveillance of HPeV3 in particular may be warranted," study co-author Ben Okaty, a geneticist at Harvard Medical School, told Live Science in an email. The team reported their findings Monday (Jan. 29) in the journal JAMA Neurology.

"It is likely that there might be other similar cases," specifically involving the HPeV3 virus, said Dr. Avindra Nath, clinical director of the National Institute of Neurological Disorders and Stroke, who was not involved in the study. "Patients should be investigated for that possibility," he told Live Science in an email.

Related: Seizures may be a cause of sudden unexplained child deaths

SIDS is the sudden death of a child younger than 1 year old that has no clear explanation, even after a thorough postmortem investigation. The cause of SIDS is thought to vary from case to case, but often, the deaths occur during sleep. The rate of SIDS dramatically declined in the 1990s in the U.S. following a government-led awareness campaign around safe sleeping practices for infants.

But since then, the rate of SIDS cases has remained fairly steady, suggesting factors besides sleep are at play.

Scientists have pinpointed potential differences in the genetics, nervous system function and enzyme activity of children who die of SIDS, compared with those who die of known causes or those who survive infancy. Some research has also pointed to neuroinflammation, meaning inflammation in the brain or spinal cord, as potentially involved in some SIDS cases.

To further investigate inflammation in SIDS, the study authors looked at clinical samples from 64 children who died of SIDS and 20 who died of known causes. They screened the clear fluid that surrounds the brain and spinal cord for signs of immune system activation and inflammation.

A compound called neopterin, which is produced by immune cells as they rev up in response to an infection, is one such sign of inflammation; it can be detected in various bodily fluids but doesn't point to a specific pathogen, only to general immune activation. Six of the children with SIDS had high neopterin levels in their samples, suggesting their nervous systems were inflamed.

To probe the causes of this inflammation, the researchers used a technique called metagenomic next-generation sequencing. 

"This type of screening isn't performed in a typical autopsy," study co-author Dr. Prashanth Ramachandran, an assistant professor of neurology at the University of California, San Francisco, told Live Science in an email.

Autopsies typically look at the shape and microscopic details of cells' structures, Nath said. Pathologists also sometimes test for specific pathogens in a tissue sample, but these tests look for known viruses and bacteria. The type of screening used in the study allowed the researchers to hunt for pathogens indiscriminately — "it provides an unbiased analysis," he said.

This screen turned up the HPeV3 in one child's fluid samples, as well as in tissues from the child's liver and several parts of the brain, such as the brainstem. HPeV3 can cause fairly mild respiratory and gastrointestinal infections, but in some cases, it can cause brain inflammation, or encephalitis.

Related: Inflammation is a 'mismatch between our evolutionary history and modern environment,' says immunologist Ruslan Medzhitov

No specific pathogen was flagged in the other five children's samples. This may be because the concentration of pathogens was too low, or that the bug triggered detectable inflammation but was cleared away by the time of death, Nath wrote in a commentary, also published in JAMA Neurology. Or alternatively, because the screening looks for genetic material, it may be that the pathogen's genetic material degraded but the proteins it made persisted and drove inflammation, he wrote.

The researchers examined the gene activity in the HPeV3-positive child's brainstem and in those of several SIDS cases without signs of neuroinflammation. This analysis uncovered distinct differences in the HPeV3-positive child. These affected genes that are activated by immune signaling molecules, as well as genes involved in brain cell maturation.

Since the brainstem helps control involuntary and life-sustaining bodily functions, such as breathing, the researchers hypothesized that infection and dysfunction in the brainstem could have contributed to the child's SIDS. The infant had become fussy and developed a fever shortly before death, but no specific pathogen had been implicated at the time.

Still, "in cases such as this, it is really difficult to know whether the child died with or died of the viral infection," said co-senior study author Robin Haynes, a principal associate in pathology at Harvard Medical School. And at this point, "we do not know whether this virus might be implicated in more SIDS cases," Haynes told Live Science in an email.

More work needs to be done to understand the virus's path into and effects on the brain, and to investigate whether other pathogens could cause similar changes in the brainstem, Haynes said. In future investigations of SIDS, more pathologists should look for signs of brain inflammation and infection as potential factors, Nath wrote in a commentary, also published in JAMA Neurology.

In future research, "our goal is to strengthen the data linking infection, neuroinflammation, and brainstem abnormalities in SIDS in such a way that provides a better understanding of mechanisms underlying known risk factors for SIDS, including minor illness prior to death," Haynes said.

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

Newborn babies' brains aren't "underdeveloped" compared with those of other primates at birth, a new study suggests.

In the past, scientists typically compared brain development between species by measuring how much each species' newborn brain size differs from its adult brain size. Compared with other primates, human babies' brains are significantly smaller than adults' brains. Meanwhile, newborn and adult primates have a smaller gap, which has led to the popular misconception that human newborns are "underdeveloped" in comparison.

In the new study, published Monday (Dec. 4) in the journal Nature Ecology & Evolution, scientists instead considered how the absolute size of the brain at birth, compared with adulthood, has varied across mammalian evolution. They found that of all mammals with a placenta, humans showed the strongest evolutionary drive toward having a proportionally small brain size at birth. However, this is not because newborn humans' brains are smaller than expected but rather that our adult brains are dramatically larger.

In other words, we're not developmentally behind primates at birth — we just have significantly more growing to do.

"Our study shows that human brains are not substantially less developed than the brains of other primates at birth, and that they simply appear so because we normally compare brain size in newborns with adult brain size, which is much bigger in humans," lead study author Aida Gomez-Robles,  an associate professor of anthropology at University College London, told Live Science in an email.

Related: In rare cases, COVID-19 infection in pregnancy can cause brain damage to fetuses

To better understand how babies' small brains stack up against other newborn animals, Gomez-Robles and colleagues analyzed brain development in modern humans, our extinct relatives the Neanderthals, and various primates, including chimpanzees, bonobos, gorillas and orangutans. In all, the study included 44 primate species, as well as dozens of additional mammals, from rodents to hooved animals and large carnivores.

They found that humans had the smallest relative brain size at birth compared with adulthood of all primates — newborn brains are less than 25% the size of adults.

Researchers believe human babies have relatively small brains because a smaller brain means childbirth is more likely to be successful.

"Classic models assume that human babies are born before they are as developed as other primates because otherwise their brains (and heads) would be too big to go through the birth canal," Gomez-Robles said. This developmental pattern ties into the fact that humans are bipedal, meaning they move around while upright on two feet, which requires a narrow pelvis compared with primates, she said.

However, human baby brains were not significantly underdeveloped compared to age-matched primates, when you consider key steps in early brain development.

When the authors focused specifically on human evolution, they found that only a few of these steps were shifted to occur after birth, instead of in the womb. These processes mainly include the insulation of nerves within brain structures, such as the hippocampus. As this makes nerves more efficient at communicating with each other, it may subsequently play a big role in driving human brain plasticity after birth, the authors wrote in the paper.

The researchers also looked at the time that human babies spend in the womb, and they found that this was no shorter than would be expected for other primates. This suggests that having relatively smaller brains as newborns is not because humans spend comparatively less time developing in the womb.

Most of the authors' results are based on estimates from mathematical models, as they were studying brain development across evolution. For example, when studying our human ancestors, they relied on approximate patterns of brain development inferred from fossilized remains.

"These estimates are valuable because they help us understand general patterns of evolution of brain development, but they are not empirical data, so they are not expected to reflect perfectly the actual ancestral values" in terms of their relative brain size over their life span, for example, Gomez-Robles said.

In future studies, the authors would like to compare these estimates with actual measurements of brain development in newborns across different species. Depending on time and resource constraints, this would be possible to a certain extent in present-day mammalian species but not in extinct species, Gomez-Robles said.

For that, they'll have to go back to the drawing board.

"The major challenge is inferring patterns of brain development in fossil hominins," our extinct ancestors, she said.

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The U.S. has a limited supply of a new drug to protect babies against respiratory syncytial virus (RSV), prompting the Centers for Disease Control and Prevention (CDC) to adjust its recommendations for how the treatment should be used in the impending RSV season.

RSV, a common respiratory virus that can cause serious illness in young children, began spreading in Florida and Georgia in late summer, and CDC data suggest that cases have been slowly ramping up elsewhere in the U.S. since then. Earlier this year, the Food and Drug Administration approved a new drug called Beyfortus (generic name nirsevimab-alip) to protect babies from the infection.

Beyfortus is a monoclonal antibody drug, meaning it contains lab-made proteins that mimic protective antibodies made by the human immune system. Whereas a vaccine would train a baby's immune system to make its own anti-RSV antibodies, Beyfortus provides a ready-made supply. The one-time shot protects children for about five months, roughly the length of an RSV season.

Related: Who should get the new RSV vaccines? Here's everything you need to know

Another, older antibody drug called Synagis (generic name palivizumab) is also approved in the U.S. But because it's expensive and requires repeat doses throughout the season, doctors have historically prescribed it only for children at the highest risk of severe RSV.

After Beyfortus' approval, the CDC originally recommended that all infants younger than 8 months old who were either born during or are just entering their first RSV season, as well as some children ages 8 months to 19 months old who are at high risk of severe infection, receive the new shot. But with treatment in short supply, the agency is dialing back its recommendation for this year.

According to Sanofi, the manufacturer of Beyfortus, the "demand for this product, especially for the 100 mg [milligram] doses used primarily for babies born before the RSV season, has been higher than anticipated." Based on Sanofi's manufacturing capacity and its currently available stock, there aren't enough 100-mg doses to protect all infants eligible for the treatment this year, the CDC said.

As such, the CDC now recommends reserving these 100-mg prefilled syringes for the infants at the very highest risk for severe RSV. This group includes infants less than 6 months old and those with certain underlying conditions, such as chronic lung disease or weakened immune systems.

"Recommendations for using 50mg doses remain unchanged at this time," the CDC noted; these lower doses are specifically reserved for infants that weigh less than 11 pounds (5 kilograms). Doctors should avoid using two 50-mg doses for infants over this weight limit, in order to preserve the 50-mg doses for smaller infants, the CDC advised.

The CDC also said doctors should stop giving Beyfortus to children 8 months to 19 months old who are eligible for the older drug, Synagis. Parents and caregivers should speak with a health care provider about which antibody drug is available and right for their child, the agency advised.

Besides using these antibody treatments, families can protect their children from RSV by washing hands, covering coughs and sneezes, cleaning frequently touched surfaces and staying home when they're sick, the CDC added. In addition, there is now an approved vaccine that can be given in pregnancy to protect newborns from the virus.

The CDC recommends that infants either be protected by this prenatal vaccine or by an antibody drug, but the agency notes that they likely don't need both.

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

Ever wonder why some people build muscle more easily than others, or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!

Respiratory syncytial virus, or RSV, is a common respiratory virus that spreads seasonally. A new drug and several vaccines that prevent the infection have recently come to market.

Here's what you need to know about the three vaccines and one injectable drug that were recently approved by the Food and Drug Administration (FDA) to fight RSV. 

Related: Who should get the new COVID vaccines? What to know about the 2023-2024 shots 

In addition to Beyfortus, an older antibody shot against RSV, called Synagis (generic name palivizumab), is available. It was first approved in 1998. However, only children at the highest risk of severe disease, not healthy children, should be given this drug, the CDC recommends.

"Palivizumab is limited to children under 24 months of age with certain conditions that place them at high risk for severe RSV disease," the CDC states. "It must be given once a month during RSV season."

For example, Synagis is recommended for premature babies, especially those with chronic lung disease, and infants with certain heart diseases. This limited usage is partly due to the drug's high cost and the fact that it requires at least one and up to five shots a month during RSV season.

Editor's note: This article was last updated on Aug. 6, 2024, after the CDC updated its guidance for which older people should get an RSV vaccine. It was originally published on Aug. 24, 2023. 

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

Ever wonder why some people build muscle more easily than others, or why freckles come out in the sun? Send us your questions about how the human body works to community@livescience.com with the subject line "Health Desk Q," and you may see your question answered on the website!  

Adoption is common among humans, who may decide to raise someone else's child for a range of reasons, including fertility struggles or the wish to provide a home for youngsters in need.

But why do animals sometimes adopt the young of others? The act of caring for an unrelated, parentless infant probably emerged because it confers an evolutionary advantage on the foster parent, said Michael Weiss, a behavioral ecologist and research director at the Center for Whale Research in Washington state. For example, adoption may provide valuable caregiving experience for females that lack offspring and increase their future young's survival chances, Weiss told Live Science.

Adoptions can occur within the same species or, in some extremely rare and puzzling cases, between different species. In a 2021 study in the journal eLife, researchers examined the effects of maternal loss on young mountain gorillas (Gorilla beringei beringei) and found that orphans over age 2 forged relationships with other group members, especially with dominant males. 

"A young gorilla would usually share its nest at night with its mother, but if the mother dies or leaves the group, then it will share a nest with the dominant male," study lead author Robin Morrison, a behavioral ecologist at the University of Zurich and an affiliate scientist with the Dian Fossey Gorilla Fund in Rwanda, told Live Science.

Mountain gorillas live in social groups composed of a dominant male and several females with their offspring. Regardless of whether the dominant male fathered the infants, his role is to protect the next generation from infanticide at the hand of rival males. His ability to do so may determine his reproductive success, Morrison said.

"Males that are really good at caring for offspring and do this in front of females are the most popular," she explained. Looking after an orphaned gorilla could earn a dominant male brownie points, thus increasing his chances of mating and of passing on his genes. "It's part of demonstrating their reproductive quality," Morrison said.

Related: What is the maximum number of biological parents an organism can have?

While the females in the group don't necessarily benefit from raising a motherless juvenile, doing so does not come at great energetic cost because infants over age 2 can forage by themselves, Morrison said. "It's also good for the other young gorillas to have a playmate," she added, as it enhances their social skills.

Social bonds and baby obsession

Adoption is also common in other primates and can bridge social groups. In a 2021 study published in the journal Scientific Reports, researchers documented the first known case of great apes adopting infants from a separate group. The team observed two female wild bonobos (Pan paniscus) that appeared to have adopted two infants from another group and posited that the behavior may boost the adults' social status. 

"One possibility is that adoptees could become future allies of the adoptive mothers," the researchers wrote in the study. "Both adoptees were females and female bonobos form strong social bonds and coalitions within their group and sometimes across groups."

Another possibility is that, like humans, female bonobos feel empathy and a fascination with infants, according to the study. "Within primate species, some adults are really baby-obsessed," Morrison said, adding that this zeal can lead to kidnappings and death if the infant is caught in a commotion.

Researchers described the kidnapping of a 3-week-old Tibetan macaque (Macaca thibetana) by a female of the same species in a 2023 study published in the journal Primates. The female had two offspring of her own when she snatched the baby from its mother, including a 1-month-old that she continued to nurse alongside the captive. The kidnapping-turned-adoption may have benefited the female by invoking future social support or favors, such as grooming, the researchers suggested. 

The kidnapping of a 5-day-old yellow baboon (Papio cynocephalus), described in a 1987 study in the American Journal of Primatology, had a less-happy ending: The infant died of starvation or dehydration after a high-ranking female abducted it and carried it around for three days. 

Underwater adoption

Nonhuman primates may feel the same caring instincts as humans do when we see a baby or small animal, which may help to explain these behaviors, Morrison said. And it's not just primates, according to Weiss, who studies orcas (Orcinus orca) in the waters around the Pacific Northwest and western Canada.

"All of the females, and especially the females who haven't had a calf yet, are totally baby-obsessed," he said. "The first year of a calf's life is the absolute center of attention for everyone."

In 2021, researchers in Iceland spotted, for the first time, an orca that appeared to have adopted a baby pilot whale (Globicephala). In June 2023, scientists with the Icelandic Orca Project were baffled by another female showing this behavior. "We are trying to piece together what is happening, but we sure have a lot of questions," they wrote on Twitter.

These cases are "a big mystery" because researchers have never seen adults from these two species socialize, which suggests the orcas may have kidnapped the baby whales, Weiss said. "The abduction case of a killer whale going into a pilot whale group and stealing a calf — while we don't know that's what happened — seems more likely to me," he added. 

A big question also remains over why this may be beneficial for orcas. Producing milk comes at a huge energetic cost, and moms nurse their calves for up to three years, Weiss said. By dividing a female's attention and draining her resources, adoptees could also pose "a bit of an issue" for any existing biological offspring, he added.

Adoptive and biological offspring may compete for attention, and this can lead to negative outcomes. In a 2019 study published in the journal Ethology, researchers documented the case of a melon-headed whale calf (Peponocephala electra) adopted by a female bottlenose dolphin (Tursiops truncatus) with a baby of her own. The adoptee repeatedly pushed the other baby from under the mother's abdomen, potentially contributing to the biological calf's disappearance shortly afterward.

The female dolphin may have felt driven to nurse the calf due to the recent birth of her own, the researchers suggested. "Both calves were approximately the same age, which could have enhanced the mother's tolerance toward a newborn during a sensitive period for establishing mother-offspring bonding," they wrote in the study. Other factors may have contributed to the adoption, such as her "curious and social personality" or her lack of caregiving experience, they added. 

Inexperience may explain why orcas showed interest in pilot whale calves. "It could be misplaced maternal instinct," Weiss said. But it could also be "takeaway lunch" to eat later or play, he added. "I wouldn't be surprised if they saw a cute little baby whale and thought 'Oh! I'll pick that up for a while.'" 

In nonmammal species too, inexperienced moms sometimes make mistakes. Common cuckoos (Cuculus canorus) are brood parasites, meaning females lay their eggs in other species' nests to save themselves the energetic cost of raising them. In a 1992 study published in the journal Behavioral Ecology, researchers found that young great reed warbler (Acrocephalus arundinaceus) females were more easily fooled by cuckoo eggs than older breeders and suggested their indiscriminate behavior could boil down to inexperience.

While evolutionary pressures can explain why animal adoptions emerged and keep happening, they may not shed light on individual cases. "One reason why that behavior might persist and keep getting passed down is because it helps build up the skills for taking care of a calf," Weiss said. "But the females are probably not doing it because they're trying to build up experience." 

Orcas, in particular, are highly intelligent creatures that we may never fully understand. "They've got big, complex brains just like us, and they have instincts and impulses, which means that they'll often do things that are really interesting and don't have an immediate survival or reproductive advantage," Weiss said.

Every newborn and infant under 8 months old should be given a "powerful" new drug to protect them from respiratory syncytial virus (RSV) this upcoming season, the Centers for Disease Control and Prevention (CDC) recommended Thursday (Aug. 3). 

The new drug isn't a vaccine, but rather contains lab-made proteins that latch onto the virus and block infection.

The recently-approved RSV drug, called Beyfortus (generic name nirsevimab-alip) is expected to become available this fall. RSV is a common respiratory infection that, in most children, causes mild, cold-like symptoms. But particularly during their first-ever bout of RSV, infants face a risk of serious lung infections, including pneumonia, where the lung's air sacs fill with fluid, and bronchiolitis, where the organ's tiny airway passages swell up.

Each year, roughly 1% to 3% of U.S. children the age of 1 are hospitalized due to RSV, the Food and Drug Administration (FDA) noted in its approval of Beyfortus. Babies born prematurely, those with chronic lung disease and those with significant congenital heart diseases face the highest risk.

Each year, 100 to 300 children under age 5 in the U.S. die of the disease, the CDC estimates.  

Related: New RSV vaccine given in pregnancy protects newborns from illness, Pfizer says 

The FDA recently approved the first-ever RSV vaccine, which is cleared for use in adults ages 60 and older. Similar vaccines for infants and children are in development but have not yet been approved. There is one RSV-preventing drug already available for infants — Synagis (generic name palivizumab) — but it's reserved for the most vulnerable children due to its high cost and the fact that it requires several injections over a short time period, STAT News reported.

Instead of training the immune system to make its own antibodies to fight RSV, as a vaccine would, the new drug gives the body a ready-made supply of them. The key component of the drug is a lab-made protein that mimics the disease-fighting antibodies normally made by the body's immune system. The Beyfortus antibody recognizes and latches onto "prefusion RSV" — the shape the virus exists in prior to infecting human cells.

The existing drug Synagis is also a lab-made antibody treatment, but Beyfortus requires only a single injection, instead of multiple.

In a 10-0 vote, a panel of advisors to the CDC recommended the widespread use of the new antibody among infants under 8 months and some high-risk children in older age groups, according to STAT News. The CDC officially adopted the recommendation hours later.

"I think this is life-changing and I'm very excited," Helen "Keipp" Talbot, an infectious disease specialist at Vanderbilt University and a member of the advisory committee told STAT News. 

The CDC recommends one shot of Beyfortus for all infants younger than 8 months old who are born during or are just entering their first RSV season. (RSV season starts in fall and runs through spring.) 

For some children between the ages of 8 months and 19 months old who are at increased risk of severe disease, including those with weakened immune systems, the CDC recommended a dose in their second RSV season.

The CDC's advisors "voted to include nirsevimab in the Vaccines for Children program, which provides recommended vaccines and immunizations at no cost to about half of the nation's children. CDC is currently working to make nirsevimab available through the Vaccines for Children program," the agency announced. (In this context, Beyfortus is considered an "immunization," or substance that boosts children's immunity, but it's not a vaccine that retrains the immune system in the long term.)

"Vaginal seeding," a controversial practice of exposing babies born by cesarean section to their parent's vaginal fluids after birth, may benefit newborns' gut microbiomes, a new study suggests.

Babies born by C-section don't have the same gut microbes as those born vaginally, potentially because they're not exposed to their parent's vaginal microbiome during birth. Studies have shown that the gut microbiomes of cesarean-born newborns more closely resemble the communities of microbes that typically inhabit the skin, rather than the gut. This has raised questions about how birth methods affect babies' development, given evidence that the community of microbes in the intestines, or gut microbiota, shapes the brain and immune system in early life.

Studies have linked cesarean births to a higher risk of neurodevelopmental disorders,  early-life infections, allergies, inflammatory diseases and metabolic diseases, and some suspect that differences in gut microbiota may contribute to this risk.

The new study, published June 15 in the journal Cell Host & Microbe, suggests that vaginal microbiota transfer (VMT), also known as vaginal seeding, is likely a safe and effective method of restoring the gut microbiome in cesarean-born infants so that it resembles that of vaginally delivered babies. 

Related: Signs of labor: 6 clues baby is on the way 

The results also hint that vaginal seeding could improve neurodevelopment in cesarean-born infants, the study authors reported. However, due to the study's small size, this potential relationship between vaginal seeding and neurodevelopment would need to be confirmed in further studies.

While vaginal seeding has become increasingly popular in the U.S., it remains controversial due to limited research on its safety and benefits. The American College of Obstetricians and Gynecologists does not recommend vaginal seeding outside the realm of research until sufficient data are available to support the practice.

The idea of restoring the gut microbiota of cesarean-born infants emerged several years ago, and vaginal seeding was proposed as a method of doing this in a 2016 paper in the journal Nature Medicine. It involves inserting a sterile gauze into the vagina before delivery, exposing it to the vaginal microbiome, and then wiping the gauze over the baby's mouth and face after birth.

Research into vaginal seeding is scant, although a recent small observational study suggested that vaginal seeding can restore the microbiota of babies born by C-section. This study included 30 infants who underwent vaginal seeding but could not definitively establish a cause-and-effect relationship between vaginal seeding and microbiota differences.

Some experts, however, have warned of the potential dangers of vaginal seeding, such as potentially exposing babies to harmful bacteria. A 2018 study even suggested that the differences in the microbiomes of cesarean- and vaginally born babies might be due to the antibiotics administered before C-sections, which can cross the placenta, rather than the babies' lack of exposure to the vaginal microbiome.

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

To establish the potential safety and benefit of vaginal seeding, researchers across multiple institutions in China conducted a clinical trial that included 68 pregnant women scheduled for C-sections. Around half of the women's babies were exposed to a gauze that contained the vaginal fluids of their mother, and the other half were exposed to a sterile saline gauze. 

The incidence of adverse events in the first 42 days after birth was similar in both groups of  babies, indicating that vaginal seeding is safe. The most common adverse events were mild skin disorders, including redness and blister-like sores; none of these events could be attributed to vaginal seeding.

The babies' gut microbiota were sampled at several points after birth, and an analysis showed that gut microbiota in the babies in the vaginal seeding group moved faster from "stunted" types to "mature" types, compared with the microbiota of the control group. 

For comparison, the team also studied the microbiomes of 33 vaginally born babies. The results showed that babies who had undergone vaginal seeding had gut microbiota that more closely resembled that of the vaginally delivered group.

The team also found that infant neurodevelopment at six months, as measured by scores on a common developmental screening questionnaire, was significantly higher for babies exposed to vaginal fluids compared with those exposed to saline, suggesting that vaginal seeding could improve neurodevelopment in cesarean-born babies. However, inferences about any potential long-term impact of vaginal seeding on neurodevelopment cannot be made since the study only measured out to six months. 

A massive hammerhead shark that recently washed up dead on a beach in Alabama was carrying 40 unborn pups, a necropsy (animal autopsy) has revealed. But it is unclear what killed the expectant mother.

The female great hammerhead (Sphyrna mokarran), which measured around 14 feet (4.3 meters) long, was discovered April 20 in the shallows near Orange Beach. A group of passersby pulled the lifeless giant onto the beach and contacted the city's coastal resources team, who recovered the corpse, city officials wrote on Facebook.  

The dead shark was in such good condition that officials contacted researchers at Mississippi State University's Marine Fisheries Ecology (MFE) group, who carried out a necropsy on the shark the next day. 

The team found that the hammerhead was carrying 40 pups, each around 1.5 feet (0.4 m) long. The brood and the mother were likely already dead before they washed ashore, according to city officials.

"While it was very sad that the shark passed," the team's findings could help vastly improve what we know about this species' reproduction, city officials wrote.

Related: Great white shark washes up on South Carolina beach in rare, unusual stranding

Great hammerheads are listed as critically endangered, according to the International Union for Conservation of Nature (IUCN) Red List of Threatened Species. There are no clear estimates on how many are left globally, but they are believed to be decreasing year on year.

During the necropsy, the team removed and examined key organs, including the mother shark's heart, liver, esophagus, stomach, spleen, kidneys and pancreas. There were no signs of trauma or disease in any of these body parts, MFE representatives wrote on Facebook. They also sent of samples from the animal's vertebrae, muscle tissue and fins to be further analyzed in the lab.

The shark's stomach was empty — normally a red flag during a necropsy — but female hammerheads often go without food for several months while pregnant, so this was expected, MFE representatives wrote.

Although MFE researchers could not determine a cause of death, they suspect it may be fishing-related. 

"We know that great hammerheads are especially prone to the physiological effects of capture stress, more so than most other shark species," they wrote, adding that pregnancy can compound this physiological stress.

Capture-induced stress was also linked to a failed shark pregnancy last year. In May 2022, a dead juvenile thresher shark (Alopias vulpinus) washed up on a U.K. beach. Experts suggested that the shark, which was not fully developed, had likely been aborted by its mother after she was accidentally caught and released by fishers.

Although the baby hammerhead sharks will never be born, they will have a second life in the education system. The pups will be preserved and donated to local classrooms to help teach children about sharks and reproduction, MFE representatives wrote.

In rare cases, COVID-19 infections in pregnancy can cross the placenta and cause fetal brain damage via harmful inflammation, two new cases suggest. Evidence presented in the paper also "raises the possibility" that the coronavirus may be able to directly infect the fetal brain.

The new report, published Thursday (April 6) in the journal Pediatrics, described two mothers who both tested positive for SARS-CoV-2, the virus that causes COVID-19, during their second trimesters of pregnancy. They caught the virus in 2020, before vaccines were available. 

Catching COVID-19 in pregnancy is known to raise the risk of other complications, such as preterm birth or preeclampsia (severely high blood pressure in pregnancy), but overall, the outcomes of affected newborns are generally good, according to the medical resource UpToDate. The authors of the new case report stressed that these cases of fetal brain damage appear to be very rare. 

"Many women are affected by COVID-19 during pregnancy, but to see these kinds of problems in their infants at birth was clearly unusual," study senior author Dr. Shahnaz Duara, medical director of the NICU at Holtz Children's Hospital in Miami, said in a statement. "We're trying to understand what made these two pregnancies different so we can direct research toward protecting vulnerable babies." 

Related: Brain shrinkage linked to COVID-19 

One mother described in the report tested positive for SARS-CoV-2 in her second trimester but developed no symptoms. She tested positive again at her time of delivery. Her newborn had seizures soon after birth. The newborn also carried antibodies that bound to the coronavirus. After her initial discharge, the baby girl was readmitted several times for seizures. At 1 year old, she was diagnosed with microcephaly, a condition in which the head is significantly smaller than average, and showed significant neurodevelopmental delay. The baby is currently in hospice care.

The second mother developed pneumonia due to COVID-19 at the end of her second trimester and was treated in the intensive care unit. She gave birth via Cesarean section about five weeks later. She and her newborn tested negative for SARS-CoV-2 at that time, but the baby had a small head, trouble breathing and seizures. The newborn also carried SARS-CoV-2 antibodies, and his brain scans revealed signs of hemorrhage (blood loss from damaged vessels). These signs later resolved, but at that point the brain showed severe atrophy, or tissue degeneration.

After being repeatedly readmitted to the hospital for infections and "failure to thrive," the baby died of cardiac arrest at 13 months old. An autopsy revealed dramatic brain tissue loss and "evidence of virus throughout the brain," the report states. 

"We became suspicious that the virus somehow managed to breach the placental barrier to damage the central nervous system, but this had not been documented before," said Dr. Ali Saad, director of the pediatric and perinatal pathology service at Holtz Children’s Hospital, said in the statement.

The coronavirus also cropped up in both mothers' placentas, along with signs of inflammation and oxygen deprivation. Strikingingly, the placentas contained remarkably little human chorionic gonadotropin, a hormone key for fetal development, including brain development.

"Most women who contract COVID go on to have healthy babies. But there is a sub-population of people who have babies who are sick," Duara said at a news briefing, The Miami Herald reported. "And so this is not to panic the population whose babies may have been exposed to COVID. But we do think that these are the extremes and we do think if you've had COVID during pregnancy, something you should tell your pediatrician, and maybe those babies need a little closer follow-up." 

Naked mole-rats are among the strangest mammals on the planet. Not only do they live longer than any other rodent ‒ up to 37 years ‒ they can also have babies well into old age. Now, scientists think they’ve worked out how: The remarkable rodents’ secret is that they never run out of egg cells.

A new study, published today (Feb. 21) in the journal Nature Communications, investigated how naked mole-rats (Heterocephalus glaber) stay fertile, and the findings challenge the belief that mammals have a limited reserve of egg cells, established before or shortly after birth, and not replenished thereafter.

"Naked mole-rats are the weirdest mammals," lead author Miguel Brieño-Enríquez, an assistant professor at Magee-Womens Research Institute and the University of Pittsburgh School of Medicine's Department of Obstetrics, Gynecology and Reproductive Sciences, said in a statement. "They're the longest-lived rodent, they almost never get cancer, they don't feel pain like other mammals, they live in underground colonies, and only the queen can have babies. But to me, the most amazing thing is that they never stop having babies."

These hairless, burrowing creatures don’t experience a drop in fertility as they get older, unlike most other mammals. But until now, scientists had no idea how.

Related: We expel carbon dioxide as waste. Naked mole rats bathe their brains in it to prevent seizures.

In the study, researchers compared the number of egg cells and death rate of these cells in mice and naked mole-rats at different stages of development. 

Most female mammals, including mice and humans, are born with a finite reserve of egg cells, which are naturally depleted over time.

But the scientists found that this is not the case with naked mole-rats. It turns out that naked mole-rat females are born without egg cells and produce an exceptionally large number of them relative to their body size as pups. As well as lasting longer than in mice, this ovarian reserve is replenished throughout the rodents' life. The researchers spotted signs of egg cells being produced in individuals up to 10 years old.

"This finding is extraordinary," senior author Dr. Ned Place, a professor at the Cornell University College of Veterinary Medicine, said in the statement. "It challenges the dogma that was established nearly 70 years ago, which stated female mammals are endowed with a finite number of eggs before or shortly after birth, without any additions being made to the ovarian reserve thereafter."

As well as adding to the naked mole-rat's long list of quirks, the researchers think these findings could lead to new therapies for humans.

Naked mole-rats live in large colonies where only one dominant female can breed. When she is displaced or dies, subordinate females compete to become reproductively active. "Any girl can become a queen," said Brieño-Enríquez. 

To find out more about the transition from subordinate female to queen, the scientists removed non-breeding females from the colony. In the absence of a queen, precursor egg cells in their ovaries started dividing — a sign of these females becoming reproductively active.

“This is important because if we can figure out how they’re able to do this, we might be able to develop new drug targets or techniques to help human health,” said Brieño-Enríquez. "Even though humans are living longer, menopause still happens at the same age. We hope to use what we are learning from the naked mole-rat to protect ovary function later in life and prolong fertility."

Editor's note: Updated at 12:25 p.m. EST to note that the study was published on Feb. 21, not Feb. 23 as was previously stated.

Editor's note: This page was last updated on Aug. 24, 2023 following the approval of various RSV vaccines and a new preventative, antibody-based drug. 

Respiratory syncytial virus, or RSV, is a very common respiratory virus, particularly among children. 

Indeed, "by age 2, 90% of people have had at least one infection" with RSV, said Dr. Octavio Ramilo, chief of infectious diseases at Nationwide Children's Hospital in Columbus, Ohio, who studies RSV. But people can catch the virus at any age, and become infected multiple times. 

In healthy children and adults, the virus typically causes mild, cold-like symptoms, but it can cause more serious disease in infants younger than 12 months old, or adults over age 65, according to the Centers for Disease Control and Prevention  (CDC). In these more serious cases, the virus spreads from the upper respiratory tract to the lungs, potentially leading to pneumonia, inflammation of the lungs' air sacs (alveoli), or bronchiolitis, inflammation of the lungs' small airway passages.

Infants are particularly at risk for severe disease because of their tiny airways — which, when inflamed, can easily compromise breathing — as well as their immature immune system, Ramilo said. 

"When you look at the number one cause of hospitalization in the first year of life, the number one is RSV," Ramilo told Live Science. It's a "very problematic pathogen," Ramilo added, and the infection leads to millions of doctor visits and thousands of hospitalizations each year.

Related: The deadliest viruses in history

What are the symptoms of RSV?

Symptoms of RSV often resemble those of the common cold. According to the CDC, typical symptoms include:

•  Runny nose/congestion 
•  Coughing 
•  Sneezing 
•  Fever 
•  Decrease in appetite 
•  Headache 

In infants, additional symptoms can include fussiness and poor feeding, according to the American Academy of Pediatrics (AAP).

Symptoms typically appear within four to six days of exposure to the virus, according to the Mayo Clinic. In severe cases, the Mayo Clinic says symptoms can also include:

•  Wheezing 
•  Difficulty breathing or rapid breathing 
•  A bluish color of the skin caused by lack of oxygen 
•  Severe cough 

People should seek immediate medical care if they experience difficulty breathing, a high fever or a blueish color of the skin, according to the Mayo Clinic. 

How does RSV spread?

RSV can spread through the air when an infected person coughs or sneezes, or through contact with contaminated surfaces. The virus can survive for up to six hours on hard surfaces, such as toys and doorknobs, and can survive for about 30 minutes on unclean hands, according to AAP. 

Children often spread the virus to others at school or in daycare settings, according to the CDC. Those who are infected with the virus are typically contagious for three to eight days; but people with an immunodeficiency may be contagious for much longer, up to four weeks and even after symptoms clear up.

Is RSV seasonal?

In the U.S., RSV typically circulates from late fall to early spring, but the exact timing in a given region can vary from year to year, according to the CDC. 

The COVID-19 pandemic also disrupted the timing of RSV season, leading to unusual summer outbreaks and earlier-than-average seasons. According to a report published in July 2021 in the CDC journal Morbidity and Mortality Weekly Report, RSV activity in the U.S. dropped to historically low levels from about April 2020 to April 2021. But when COVID-19 restrictions began to lift in the spring of 2021, RSV surged, leading to a summer spike in RSV infections, the report said.

The reason behind these trends still isn't clear, Ramilo said. Although some experts suspect that measures to reduce the spread of COVID-19 taken in 2020, such as mask-wearing and social distancing, also reduced the spread of RSV, Ramilo said he doesn't think this is the whole story. "I don't think we can explain everything from nonpharmaceutical interventions" like masking wearing and social distancing, said Ramilo, who noted that other respiratory viruses, such as rhinovirus and adenovirus, still circulated in 2020, despite restrictions. 

What is clear is that the summer of 2021 saw a dramatic increase in RSV hospitalizations. "Here, we saw a big increase in July and August," at the same level that's usually seen in December or January, Ramilo said. In 25 years of studying RSV, "this is the first time we've seen an outbreak in the middle of July and August," he said.

Related: 20 of the worst epidemics and pandemics in history

Is RSV the same as COVID-19?

RSV is different from COVID-19. RSV belongs to a family of viruses known as pneumoviruses, whereas SARS-CoV-2, the virus that causes COVID-19, belongs to a group of viruses known as coronaviruses. Since RSV and SARS-CoV-2 are both respiratory viruses, their symptoms can be similar, according to the Mayo Clinic.

It is possible to be infected with both RSV and COVID-19, but such coinfections do not appear to be common, Ramilo said. Doctors have been on the lookout for these coinfections because it's known that children can sometimes be infected with RSV and other coronaviruses that cause the common cold, Ramilo said. But "we haven't seen very many cases [of RSV and COVID-19 coinfections], just a handful," he said.

What are the risk factors for RSV?

According to the CDC and AAP, people at risk for severe RSV infections include:

•  Premature babies, particularly those born before 29 weeks 
•  Children younger than 2 years old with congenital heart disease or chronic lung disease 
•  Children or adults with weakened immune systems due to a medical condition (such as cancer) or medical treatment (such as an organ transplant) 
•  Adults older than 65, especially those with chronic heart or lung disease 

Every year in the U.S., the virus leads to approximately 2.1 million doctor's visits among children younger than 5 and about 58,000 to 80,000 hospitalizations in the same age group, the CDC estimates. It's the most common cause of hospitalization in infants, and annually, 100 to 300 children under 5 die from the infection in the U.S.

Among adults ages 65 and older, RSV leads to 60,000 to 160,000 hospitalizations each year and about 6,000 to 10,000 deaths in the U.S.

 Related: 28 devastating infectious diseases 

How is RSV treated?

There's no specific treatment for RSV. Because RSV is caused by a virus, not a bacterium, antibiotics won't work to treat the infection. Most people who catch RSV get better within a week or two without medical intervention.

Over-the-counter medicines, such as acetaminophen or ibuprofen, can help manage symptoms, such as pain and fever. Children should never take aspirin, according to the CDC. People can also use nasal saline drops and suctioning to help with a stuffy nose, according to the Mayo Clinic. Those with an infection should drink plenty of fluids to stay hydrated. 

RSV may also increase the risk of ear infections in children, according to the AAP. If a child develops a bacterial ear infection, their doctor may prescribe antibiotics.

In rare cases, people with RSV are hospitalized, and their treatment in the hospital may include fluids, additional oxygen or use of a mechanical ventilator to help with breathing.

In the U.S., about 3% of infants with RSV infection need to be hospitalized, Ramilo said. But most are able to go home within two to three days, according to the AAP. 

How to prevent RSV spread

Basic hygiene measures can reduce the risk of RSV infection, according to the Mayo Clinic, including:

•  Frequent hand washing 
•  Regular cleaning of frequently-touched surfaces, such as doorknobs, as well as children's toys 
•  Covering coughs and sneezes (with your sleeve rather than your hands.) 
•  Avoiding contact with sick people 

People who have cold symptoms should steer clear of those at risk for severe disease from RSV.

Is there a vaccine for RSV?

There are two FDA-approved vaccines for RSV — one for older adults, and one for both older adults and pregnant people. 

The FDA approved the first-ever RSV vaccine in May 2023. The shot, called Arexvy and made by the pharmaceutical company GSK, is approved for adults ages 60 and older.

The vaccine contains an adjuvant, a substance that revs up the immune system, and a lab-made version of a protein found on the surface of the virus. The virus uses this fusion, or "F" protein, to break into cells. The shot trains the immune system to recognize what the F protein looks like in its "prefusion" form, the shape it's in before it infects cells.

The second RSV vaccine approved by the FDA is called Abrysvo. Made by Pfizer, the shot was approved for older adults in May 2023 and for pregnant people in August 2023. Like Arexvy, Abrysvo contains lab-made perfusion F proteins. Neither vaccine contains preservatives, according to their drug labels.

Read more about the vaccines and who should get them.

Are there drugs to prevent RSV?

There are two antibody-based drugs available to protect infants and some young children from RSV.

These injectable drugs, called monoclonal antibodies, are given to infants during their first RSV season. And some older children at high risk of infection are recommended the shots in their second RSV season. 

The shots contains lab-made proteins that mimic antibodies made by the immune system. This type of drug doesn't train a child's immune system to make its own RSV-fighting antibodies, like a vaccine would. Instead it provides a ready-made supply.

Read more about the monoclonal antibodies, who should get them and when. 

Additional resources

Read more about RSV in infants and children, from the American Academy of Pediatrics. Get more details on RSV symptoms and care, from the CDC. Find information on RSV risks and complications, from the Mayo Clinic. 

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

More than 3.8 million babies were born each year in the United States on average from 2010 to 2020, according to the National Center for Health Statistics. But in which month are the most babies born, and why?

In the United States, the month with the largest number of births is typically August, with July a close second, Brady Hamilton, a demographer with the National Center for Health Statistics, told Live Science.

For example, August saw the greatest number of births in eight of the years from 2010 to 2020, Hamilton noted. July nabbed first place in three of those years — 2014, 2015 and 2020, he said.

Related: What is the birthday paradox?

In 2021, August was again the leading month, seeing 329,978 births, compared with an average of 350,067 births from 2010 to 2020. The smallest number of births in 2021 occurred in February, which saw 266,308 births, according to the National Center for Health Statistics.

Since the full course of a pregnancy is normally about 40 weeks, or a little more than nine months, these data suggest most children in the United States are conceived in November or December, Hamilton noted. "It's a fascinating question why that is," Hamilton said.

Reproduction appears to be seasonal in many living organisms — including plants, insects, reptiles, birds and  mammals — likely to help maximize their chances of reproduction over the course of their lifetimes, Micaela Martinez, an assistant professor of environmental health sciences at Columbia University in New York, and Kevin Bakker, previously an assistant research scientist at the University of Michigan and now a principal scientist at Merck, wrote in an essay for The Conversation.

In a 2014 study in the journal Proceedings of the Royal Society B: Biological Sciences, Martinez, Bakker and their colleagues noted that there was a clear pattern of births across latitudes in the United States: Northern states have a birth peak in June and July, whereas Southern states experience a birth peak later, in October and November.

The 2014 study found a similar pattern across the Northern Hemisphere, with peaks occurring later in the year the closer the location was to the equator. For instance, Finland saw the most births in late April, whereas Jamaica's births peaked in November.

So what could explain this correlation?

A 1990 study in the Journal of Biological Rhythms suggested the seasonality of human births may be linked with local temperature and day length. The extent to which temperature and day length may or may not change seasonally over the year depends in part on latitude, Martinez and Bakker noted. These environmental changes may influence the frequency of sex or how fertile men or women are, they noted. However, in their 2014 study, they note many other factors may play a role as well, such as income, culture, holidays and rainfall, making it challenging discussing whether and in what way temperature or day length might affect human births.

Understanding when most human births happen is more than just a matter of trivia, Hamilton said.

"If you're the birthing ward of a hospital, or a company that makes baby formula, or a diaper manufacturer, it's good to know what you might be facing over time," Hamilton said. "Further down the line, school systems may want to anticipate how many children may be coming in at a certain point in time, and health care systems would want to know what to expect in terms of inoculations."

Originally published on Live Science on July 27, 2010 and rewritten on Aug. 19, 2022.

In an extremely rare case, a Texas woman became pregnant while already pregnant and ultimately gave birth to twins who had been conceived roughly one week apart, according to news reports. 

The 30-year-old woman, named Cara Winhold, initially learned she was pregnant in March 2021, and when she received an ultrasound five weeks later, there appeared to be just one embryo developing in her uterus, the Daily Mail reported. However, since Winhold had a history of miscarriages, her doctor asked that she come in for another scan just two weeks later, to check that the pregnancy was still progressing well. At that follow-up, not one, but two implanted embryos popped up on the scan. 

"On the very first scan, there was a sac with one baby and then when I went back there was a really tiny little sac in the corner that had another baby in it," Winhold told the Daily Mail. "You could see baby A was more developed, whereas the other one was like a tiny dot." 

This rare phenomenon, in which a second pregnancy occurs in the midst of another pregnancy, is known as "superfetation." 

Related: Woman gives birth to twins — 11 weeks apart

Few cases of superfetation are described in the medical literature, but of those reported, most have occurred in women undergoing fertility treatments, such as in vitro fertilization (IVF), according to Healthline. This procedure involves transferring fertilized embryos into the uterus, and superfetation may occur if the patient then ovulates and that released egg gets fertilized in the weeks following the transfer. 

In Winhold's case, she had not undergone any fertility treatments, she told the Daily Mail. Such cases are considered exceptionally rare, in part, because three unlikely events must happen simultaneously, Live Science previously reported.

First, an ovary must release another egg, or ovum; this typically doesn't occur because, at the start of pregnancy, the body releases hormones to halt ovulation. Second, that egg must be fertilized by a sperm cell; this is improbable because mucus builds up in the cervical canal in early pregnancy, forming a "plug" that blocks the passage of sperm. And finally, the fertilized egg must implant in the uterus. With one embryo already implanted and developing, there may not be much room for a second. Typically, specific hormones are released during implantation to help the process along, and this release wouldn't happen with a pregnancy already underway. 

If all these improbable events occur, two pregnancies will ensue at the same time, but the resulting fetuses will be two different gestational ages, meaning they'll be at different stages of development. (This differentiates such twins from fraternal twins, who develop from two fertilized eggs but are the same gestational age, according to the Live Science report.) Winhold said that, according to her doctor, "most likely I ovulated twice, released two eggs, and they got fertilized at different times, about a week apart," she told the Daily Mail.

Winhold gave birth to her rare set of twins in October 2021, according to the Daily Mail. Colson, the baby who was conceived first, was slightly larger than his twin, Cayden, at birth and still outweighed him at their six-month checkup.

Originally published on Live Science.

Babies under 12 months old should drink either human breast milk or infant formula — and not cow's milk, according to the American Academy of Pediatrics. So, is cow-made milk dangerous for little ones?

Human milk is produced specifically for human babies, whereas cow's milk is really for calves, Dr. Jae Kim, director of the Division of Neonatology at Cincinnati Children's Hospital, told Live Science. As such, cow's milk contains proteins that are hard for babies to digest, and it lacks key vitamins and minerals, such as iron, that babies need to develop. Even though infant formula is made from cow's milk, manufacturers remove the proteins and alter them before adding them back to the formula, along with other essential ingredients. "The final infant formula is quite different from the dairy milk you get," Kim said.

An infant's gut, kidneys and immune system need time to mature before they can safely tolerate new types and amounts of protein found in cow’s milk, Kim said. High concentrations of the protein and minerals found in cow's milk "can stress a newborn's immature kidneys and cause severe illness at times of heat stress, fever or diarrhea," according to the American Academy of Pediatrics (AAP). That's why "we've really recommended strongly to avoid cow's milk for the first year of life," Kim said. While the vast majority of babies over 6 months will do fine drinking cow's milk, the foreign protein can cause inflammation through an allergic response in some babies, Kim said.

Related: Why do babies babble?

That allergic response can lead to inflammation in a baby's gut or microscopic bleeding in their intestinal lining, according to Kim. And the lack of iron in cow's milk can lead to anemia. Overall, it can result in babies being unwell or not thriving, he said. 

This risk is lower in older infants who, starting around 4 to 5 months, eat more than just formula, Kim added. Because milk isn't their only source of nutrition, they are more likely to get adequate nutrients elsewhere. Plus, older babies have a more mature gut, kidneys and immune system to tolerate the new proteins. But because newborns and young infants consume only milk, it's more important for them to receive a very careful formulation like breast milk or infant formula, Kim said. 

However, cow's milk for infants under age 1 "is not ideal and should not become routine," the AAP said. It is a better option, though, "than diluting formula or making homemade formula," according to the AAP. 

In cases in which supplementing with cow's milk for a short period of time may be necessary, such as the 2022 infant formula shortage in the U.S., transition to cow's milk slowly if you can, so that it doesn't shock the baby's system, Kim said. And be mindful of signs and symptoms of any inflammatory or allergic reaction, he added. Babies likely won't have an immediate reaction to the cow's milk, but instead they may gradually start to spit up or have diarrhea more often. Worst-case scenario, there could be some blood in their stool due to colitis, an inflammation in the colon. Or they can become swollen, particularly their face, and anemic from protein loss in the blood, he said. 

For babies who have already had a dairy aversion or who need a special formula that contains only broken-down proteins or amino acids, dairy milk before they're a year old probably won't be suitable. And plant-based milks, which are much lower in nutritional content, are not an adequate nutritional substitute for any baby, Kim said. But for the vast majority of infants 6 months and older, the addition of cow's milk shouldn't cause a problem, he said. If you do have concerns about what your baby should be drinking, the AAP advises that you talk with your pediatrician. 

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

Originally published on Live Science.

A brain structure called the amygdala grows too fast in babies who are diagnosed with autism by age 2, a new study suggests.

The study researchers found that this overgrowth occurs between 6 and 12 months of age, before children are typically diagnosed with autism. The findings, published Friday (March 25) in The American Journal of Psychiatry, suggest that therapies for children at high risk of autism may have the best chance of working if they start in infancy.

"Our research suggests an optimal time to start interventions and support children who are at highest likelihood of developing autism may be during the first year of life," study senior author Dr. Joseph Piven, a professor of psychiatry and pediatrics at the University of North Carolina at Chapel Hill, said in a statement.

Autism spectrum disorder (ASD) is a developmental disorder that affects how a person communicates, interacts socially, learns and behaves, according to the National Institute of Mental Health.

The amygdala is an almond-shaped structure deep in the brain that's involved with processing emotions, including feelings of fear, as well as interpreting facial expressions. Researchers already knew that the amygdala appears larger in school-age children with ASD compared with children without ASD, but exactly when this enlargement starts was not known.

Related: 10 things you didn't know about the brain

In the new study, researchers scanned the brains of more than 400 infants, including 270 who were at higher risk of developing autism because they had an older sibling with the condition; 109 infants with typical development; and 29 infants with Fragile X syndrome, a genetic disorder that causes developmental and intellectual disability. The children underwent MRI scans at ages 6 months, 12 months and 24 months. By age 24 months, 58 (or about 21%) of the at-risk children had been diagnosed with ASD.

The researchers found that at age 6 months, all of the children had similar-sized amygdalae. But by 12 months, the children who would later develop autism had enlarged amygdalae compared with children who didn't develop autism and those with Fragile X syndrome. What's more, those with the fastest rate of amygdala growth had the most severe symptoms of autism.

"The faster the amygdala grew in infancy, the more social difficulties the child showed when diagnosed with autism a year later," study first author Mark Shen, an assistant professor of psychiatry and neuroscience at UNC Chapel Hill, said in the statement.

The researchers hypothesized that early problems with  visual and sensory information processing in infancy may put stress on the amygdala, resulting in its overgrowth. (The amygdala receives signals from the brain's visual system and other sensory systems in order to detect threats)

Studies have found that children that go on to be diagnosed with autism have problems as babies with how they pay attention to visual stimuli.

Interventions in babies at high risk of autism might want to focus on improving visual and other sensory information processing in babies, Piven said.

Early interventions for autism usually begin around two or three years of age, when a child is diagnosed with autism, according to the National Institutes of Health. However, some studies have tested interventions in babies that were at risk for autism because they had a sibling with autism or in babies that showed early symptoms, such as visually fixating on certain objects, according to the autism news site Spectrum. For example, a small 2014 study tested an intervention in children ages 6 to 15 months, which taught parents new ways of interacting with their babies, such as methods to shift the baby's attention away from an object they were fixated on; and found that the therapy reduced autism symptoms by age 3, Spectrum reported.

Originally published on Live Science. 

Beginning in the second trimester of pregnancy, an expecting parent may feel their unborn baby kicking, rolling over and even hiccuping. But is it known whether babies can start crying before they're born? 

Although pregnant people can't feel this movement, research suggests that babies do seem to start practicing for this big birth milestone before they've taken their first gulp of air.

Ultrasound technologies have allowed us to peer inside the uterus and observe fetuses while they're still developing. For example, a video published in the journal Archives of Disease in Childhood — Fetal and Neonatal Edition in 2005 shows a 33-week fetus making facial expressions that look like crying through an ultrasound profile. After the researchers gave the fetus a vibration and noise stimulation, it opens its jaw wide, tucks in its chin and lets out three big exhales in a row as its chest rises and its head tilts back, ending with a chin quiver. This movement was seen in 10 fetuses (about 6% of the total number of babies scanned).

Related: What happens when a baby takes its first breath?

So, was this fetus crying in the womb? It depends on how you define crying. "If you use the definition of 'a loud inarticulate shout or scream expressing a powerful feeling or emotion,' then you can say quite definitely that babies don't cry in the womb," Nadja Reissland, a developmental psychologist at Durham University in the U.K., told Live Science in an email. 

Put another way, in the fluid-filled amniotic sac, fetuses can't take in a big breath, fill their lungs and vibrate the air through their vocal cords to start to wail — that will need to wait for the first visit to the outside world. 

Reissland's team has analyzed the development of facial expressions in utero by watching the movements of fetuses in the second and third trimesters through 4D ultrasound imaging — 3D movies of fetal actions. These facial expressions — including the "cry-face-gestalt" and the "laughter-gestalt" that Reissland and colleagues defined in a paper published in the journal PLOS One in 2011 — may be precursors to the facial expressions used outside the womb.

These preliminary facial expressions develop around 24 to 35 weeks, and their complexity increases with gestational age. These motions are too subtle to be felt by the pregnant parent, Reissland said. But the fetus seems to be practicing at least the facial movements of crying before birth, preparing it to become functional when they take their first breath and let out that long-awaited wail signaling their arrival. Whether they're vibrating the vocal cords and trying to make sounds in utero is not possible to know. Even if they did manage to make a sound wave in the fluid, it likely wouldn’t be strong enough to travel through the amniotic fluid and flesh of the mother.

We also don't know that these crying motions are in any way linked to pain or discomfort in the fetus. In Reissland's studies, the fetuses showed these facial expressions without stimulation of any kind; the expressions they observed weren’t in response to any stimulation by the researchers. 

Facial expressions play an important role in postnatal bonding and communication between the parent and child, Reissland said. These facial gestalts may act as a kind of trial run for the facial muscles — this practice in the womb may help the baby bond with others once they’re born. 

Reissland's goal in studying these facial expressions is to help researchers develop a useful tool for identifying developmental disorders and other health problems in utero. A fetus with a developmental or health issue might not show these facial expressions at the same time as a healthy fetus would. 

The development of full facial expressions is learned after birth in the social context of interacting with people, Reissland said. Babies don't start "socially" smiling until about 8 weeks, and those precious baby giggles don't come until roughly 4 to 6 months, but their faces are developing these abilities weeks before birth. Fetuses don't produce tears, either; crying with tears doesn't typically begin until around four weeks after birth, once babies' tear ducts are mature enough to form teardrops, Live Science previously reported.

Originally published on Live Science.

Within seconds of birth, a baby takes in its own oxygen for the first time. For that to happen, their tiny lungs and circulatory system have to transform in a matter of seconds. So how does a tiny human manage to take what could be the most challenging breath of its life just seconds after birth? 

First, it helps to understand how the circulatory system — specifically, the lungs and heart  — work in utero. The lungs don't provide oxygen to the fetus during gestation. Instead, they are partially collapsed and filled with liquid during development while the baby gets oxygen through the umbilical cord from the placenta, according to the Texas Heart Institute. 

Because the lungs aren't involved with oxygen supply yet, the majority of the fetal blood supply bypasses the lung through two blood vessels unique to fetuses. The first, the foramen ovale, allows oxygenated blood from the umbilical cord to flow directly from the right atrium of the heart to the left atrium, instead of going to the right ventricle and lungs as it does in an adult, according to the Children’s Hospital of Philadelphia. The second vessel, called the ductus arteriosus, connects the main body artery and main lung artery, allowing the fetus's oxygenated blood to detour away from the lungs and head for the lower body, according to the American Heart Association. 

Related: How much blood is in the human body?

Unlike an adult heart, "when the baby comes out, the right side of the heart is the dominant side," said Dr. Jae Kim, a neonatologist and director of neonatology at Cincinnati Children's Hospital. This is because it's been pumping oxygenated blood through these two temporary shunts to the entire body. But after birth, the circulatory system rearranges. The left ventricle becomes dominant, responsible for sending blood throughout the body, while the right ventricle takes on the new job of sending oxygen-poor blood to the lungs, according to a 2002 report published in the journal Archives of Disease in Childhood. 

This transformation happens in a series of rapid changes right after birth. First, the cells responsible for secreting fluid in the fetus's lungs start absorbing fluid once the baby is born, removing the liquid to make room for incoming oxygen, Kim said. "The lungs immediately transition to be filled with air." This first breath can be so strong and dramatic that, in some cases, it bursts a hole in the baby's nascent lungs, he said. 

This first inflation of the lungs dramatically decreases the pressure and resistance to blood flow in the lungs. The low pressure invites blood pumping out of the right ventricle to reroute toward the neonatal lungs, according to a 2010 review in the journal Physiological Reviews.

Once the lung pressure is lower than the systemic blood pressure, or the pressure exerted on blood vessels during heart contractions, the foramen ovale closes, according to the 2010 review. With no passage between the right and left atria, deoxygenated blood begins to flow from the right atrium to the lower right ventricle, and is then sent to the lungs.

Meanwhile, the low pressure in the pulmonary system detracts blood from the ductus arteriosus, the blood vessel that allowed blood to bypass the lung and head to the body. No longer needed, the ductus begins to constrict and closes within the first two days of life.

At this point, 100% of the infant's blood supply heads for the lungs. Carbon dioxide-saturated blood is pumped into the alveolar capillaries — small blood vessels in the lungs — for the first time. The alveoli — tiny air sacs in the lungs — replace carbon dioxide in the blood with the oxygen taken in by the baby. 

It takes about 5 minutes for a healthy baby born at term to "pink up" and find a sort of normal, Kim said. But the transition happens in a single breath. "It's a very magical moment," he said. 

Originally published on Live Science.

Sometimes when ape or monkey infants die, their mothers continue to groom and hold the tiny corpses for days, weeks or months, even as the babies' bodies decay or become mummified. That distressing behavior is more widespread than previously thought, a new study finds.

Researchers recently conducted the first analysis to compare more than 400 documented cases of primate mothers interacting with their dead infants, collecting examples from more than a century of observations covering 50 primate species. The scientists then created "the largest database of primate mothers' responses to their infants' death," they wrote in a new study. 

They also discovered that factors such as the mother's and infant's ages, and the suddenness of the youngster's death could shape a mother's actions toward her infant after it died. 

Related: In photos: Macaque mother cares for mummified corpse of daughter

Scientists have published descriptions of infant corpse-carrying in primates since the early 20th century; one of the first accounts dates to 1915, appearing in the Journal of Animal Behavior, said lead study author Elisa Fernández-Fueyo, a primatologist and graduate student in the Department of Anthropology at the University College London (UCL) in the United Kingdom.

In the 1915 study, primatologist and psychologist Robert Yerkes "reported the case of a captive rhesus macaque mother who carried her dead infant for five weeks," and he suggested in the study that the mother's behavior was a manifestation of maternal instinct, Fernández-Fueyo told Live Science in an email. 

For the new study, the authors analyzed reports dating from 1915 to 2020 of monkeys, apes, bushbabies and lemurs that tended to their deceased young. Roughly 80% of the species they reviewed performed corpse-carrying behavior. However, this activity was most frequently reported in great apes — our closest primate relatives — and Old World monkeys. Both of those primate groups "also carry their infants after death for the longest durations," Fernández-Fueyo said.

For example, in March 2020, researchers described 12 cases of baboon mothers in the wild carrying their dead babies for as long as 10 days. In 2017, a female macaque (a genus of Old World monkey) in an Italian wildlife park carried her dead infant for four weeks, eventually cannibalizing the mummified corpse. And in 2003, after two infant chimpanzees died of respiratory ailments, their mothers carried the babies' corpses for months, Live Science previously reported.

Expressing grief

Lemurs, which diverged from other primate groups more than 60 million years ago, were an exception in the new analysis, and they did not carry deceased infants, Fernández-Fueyo said. However, lemur mothers "were still found to express grief through other behaviors, such as returning to the corpse or giving mother-infant contact calls," Fernández-Fueyo said.

In the species that were reluctant to give up their dead infants, corpse-carrying may occur because the cause of the baby's death isn't visibly obvious (for example, when the baby dies from an illness, rather than from traumatic injury), or when the mother is young and has less direct experience with death than an older female might have, according to the study.

And the length of time that females carried the corpses could indicate the strength of the emotional connection between mother and infant, the authors suggested.

"It is known that the mother-infant bond is regulated by emotions in primates — for example, mother separation from live infants causes anxiety in the mother," Fernández-Fueyo said. In other words, separation anxiety could be a trigger for infant corpse-carrying in primates, and it could explain why the corpses of very young, unweaned infants were typically carried for longer than older babies were, the scientists reported.

In fact, some primate mothers that carried their dead babies would give alarm calls — a sign of stress — if they lost the corpse or if it was taken from them, "suggesting that carrying the corpse may be a way of coping with the stress related with the loss," Fernández-Fueyo said. "More data is needed to further develop our understanding of this, and of how much primate behaviors relating to death may not only be explained by bonds but also by the associated emotions — and, thus, resemble human grief."

The findings were published Sept. 15 in the journal Proceedings of the Royal Society B: Biological Sciences.

Originally published on Live Science.

A baby in Israel was born with her own "twin" inside her stomach — a rare phenomenon known as "fetus in fetu," according to news reports.

Doctors first realized there might be a problem when they performed a late-pregnancy ultrasound on the baby's mother and saw that the baby's stomach was enlarged, according to The Times of Israel.

So when the baby was born, doctors performed a number of tests, including ultrasounds and X-rays, and spotted a partially developed fetus inside the baby's abdomen, The Times of Israel reported. Doctors performed an operation to remove the fetus.

Related: Seeing double: 8 fascinating facts about twins

The term "fetus in fetu," which literally means "fetus within fetus," is generally defined as a condition in which a developmentally abnormal fetus is found inside the body of its otherwise healthy twin, Live Science previously reported. The condition is extremely rare, occurring in about 1 in 500,000 births, according to a 2010 report on the phenomenon, published in the Journal of Surgical Technique and Case Report. 

It is not exactly clear what causes fetus in fetu, but scientists think the fetus is a a rare type of "parasitic twin," according to Arizona State University. Such parasitic twins form when, during an identical-twin pregnancy, one of the fetuses is absorbed by the other early in pregnancy.

"It happens as part of the fetal development process when there are cavities that close during development and one of the embryos enters such a space," Dr. Omer Globus, director of neonatology at Assuta Medical Center in Ashdod, Israel, where the baby was born, told The Times of Israel. "The fetus inside partially develops but does not live and remains there."

Another theory is that fetus in fetu is a kind of teratoma, a type of tumor that can contain all three of the major cell types that are found in an early-stage human embryo, Live Science previously reported. Some researchers say that the presence of a spinal column distinguishes a diagnosis of fetus in fetu from a teratoma, with the latter lacking a spinal column, according to the 2010 paper. 

The baby is recovering well from her operation and is now at home with her mother, The Times of Israel reported.

Originally published on Live Science.  

A baby underwent surgery in the womb for spina bifida, and since being born six weeks ago, the child is healthy and developing well, according to a statement from the Great Ormond Street Hospital (GOSH) for Children in London.

Spina bifida occurs when the so-called neural tube, a hollow structure that begins forming around the third week of pregnancy, does not develop properly and essentially ends up with a hole in it, according to the Centers for Disease Control and Prevention (CDC). The neural tube later gives rise to the baby's brain and spinal cord, so a hole in the structure can cause mild to severe nerve damage and result in physical and intellectual disabilities.

Helena, a mother in the U.K., learned her developing baby had spina bifida during her 20th week of pregnancy, according to the statement. 

"It was a very large lesion on her back and half of her spine was exposed," Helena told BBC News. "They said that it was likely she will be paralyzed, incontinent and will need a shunt to drain the fluid from her brain later on."

Related: 12 amazing images in medicine

Thankfully, in 2011, a landmark clinical trial showed that operating on babies in the womb could spare them from some of the harmful effects of spina bifida, Live Science previously reported. Compared with babies with spina bifida who received surgery after birth, those operated on in the womb were twice as likely to walk without assistance by the age of 2 and developed fewer neurological problems.

The open fetal surgery does carry some risks, as it somewhat raises the risk of premature birth and requires mothers to deliver via C-section, or else risk rupturing the uterus, according to Live Science. 

"The procedure is complex, time-sensitive and not without its risks, but the significant and life-changing impact on babies … and their families, cannot be overstated," Dr. Dominic Thompson, lead neurosurgeon at GOSH, said in the statement. "This makes all the difference to the quality of their lives."

Helen's operation involved 25 clinicians from GOSH and University College London Hospitals, as well as University Hospitals Leuven in Belgium, where the surgery was conducted, according to BBC News. 

In general, the procedure involves giving an anesthetic to the mother, which also passes to the fetus, and then cutting through the abdomen and uterus to reach the fetus's spine, according to the GOSH statement. Neurosurgeons then separate any skin attached to the exposed spinal cord and place the cord inside the spinal canal before stitching the tissues closed. 

Helena received surgery in her 23rd week of pregnancy, and three months later, she gave birth to her daughter Mila at University College London Hospital. There is still some excess fluid on the newborn's brain, but so far, Mila is showing signs of healthy development, according to the GOSH statement.

"She can move her legs, and she's got feeling to her toes so it's absolutely amazing," Helena told BBC News. "I'm just so grateful to the surgeons who've done this operation because her life would look very different without it." Including Mila, the team has performed the same operation on 32 babies since January 2020.

"We're very excited about the next phase of the prenatal surgery for babies with spina bifida, including less invasive approaches," Dr. Paolo De Coppi, part of the fetal surgical team for spina bifida, said in the statement.

Since 2011, several groups have developed less invasive versions of the fetal surgery that only require minor incisions in the uterus and thus pose fewer risks to both mother and child, Stat News reported. And some doctors have developed techniques to avoid making large incisions in either the uterus or the abdomen, but as of 2019, this approach was still quite new and not widespread.

"As with any new approach, we first need to fully understand the benefits and risks involved to mother and baby," De Coppi noted. "While we look to make these future procedures as safe as possible, what is clear is that prenatal surgery for patients with spina bifida leads to better outcomes."

Originally published on Live Science.

The series "Imaginary Earths" speculates what the world might be like if one key aspect of life changed, whether related to the planet or humanity.

The sex of humans is largely controlled by the X and Y sex chromosomes. However, in many reptiles and fish, sex is instead influenced by how warm or cool eggs are before hatching. What might life be like for humans if sex was likewise under the sway of temperature?

The fact it was even possible to control the sex of animals using heat or cold was first uncovered in the rainbow agama lizard in 1966 by French zoologist Madeline Charnier at the University of Dakar in Senegal. She found hatchlings from eggs incubated at lower temperatures were female, while those that developed at higher temperatures were male.

Since then, scientists have discovered other patterns of temperature-dependent sex determination. For instance, with the Hawaiian green sea turtle, females emerge if incubated above a certain temperature and males if below a certain temperature, and if temperatures in nests fluctuate between those extremes, a mix of males and females are seen, according to a 2020 study published in the journal Bionatura. In contrast, with the American alligator, females develop from extremes of hot and cold and males from intermediate temperatures. 

Related: What if humans had photosynthetic skin?

Temperature controls sex determination, in all crocodilians, most turtles, many fish, and some lizards, according to organismal biologist Karla Moeller at Arizona State University. Within a specific window of time during the embryonic development of these animals, heat or cold can influence the production of sex hormones, which in turn can sway a hatchling's fate.

Moeller noted that one cause of temperature-dependent sex determination is an enzyme known as aromatase, which can convert male sex hormones to female sex hormones. In animals such as the red-eared slider turtle, heat during a specific developmental stage can increase levels of this enzyme, leading to more females.

Evolutionary mysteries

It remains uncertain exactly why these animals practice temperature-dependent sex determination, although a huge number of theories exist, Jennifer Graves, a geneticist at La Trobe University in Melbourne, Australia, told Live Science in a phone interview.

"Our best guess is that temperature-dependent sex determination originated because reptiles do not have parental care and the eggs are in close interaction with the environment," Diego Cortez, a biologist at the National Autonomous University of Mexico in Mexico City, told Live Science in an email. "We also know that elevated incubation temperatures speed up the development of embryos. So, the sex that is linked to higher incubation temperatures will hatch earlier." 

Because, among reptiles, hatching is often linked with the rainy season, when life flourishes, any hatchling that emerges early will likely get more food, Cortez said. "With more food, it will grow faster, and will have higher chances of surviving until it reaches maturity," he said.

According to this idea, known as the survival-to-maturity hypothesis, "if for some reason it is better for a species to have larger females or larger males at maturity, then this sex will be linked to high incubation temperatures so it can hatch earlier during the season," Cortez said. 

Another possibility is that temperature-dependent sex determination could give a way for mothers to control the sex of their offspring. Scientists have suggested that female alligators may choose cooler nests to have more female hatchlings, so when populations are low, "females can make their nests down near the water so more females hatch," Graves said. In contrast, when populations have reached a stable level, females might choose warmer nests "so there are a lot more males, getting more male aggression and competition." The next generation of females could then choose from the best males, Graves suggested.

Unlikely in humans?

All known species with temperature-dependent sex determination are both oviparous, or egg-layers, and cold-blooded, meaning their body temperatures change with that of their surroundings. However, humans are neither of those things.

Related: Why do animals hibernate?

As such, "temperature-dependent sex determination in humans is not very likely because you would need, at a minimum, two different body temperatures — one that would trigger female development and one that would trigger male development," Cortez said. "But the human body is always at 37 degrees Celsius (98.6 degrees Fahrenheit)."

Still, if women could somehow experience a range of body temperatures, Cortez said he could imagine a way for temperature-dependent sex determination to happen in humans. He noted that some proteins that help regulate circadian rhythms in humans — our internal clocks — are also linked with temperature-dependent sex determination in reptiles. These proteins, known as CLK kinases, are found throughout the body, and can sense very small fluctuations in body temperature.

"It would not be impossible to think that if CLK kinases are involved in temperature-dependent sex determination in reptiles, where they sense large changes in incubation temperatures — usually between 3 and 7 degrees Celsius [5.4 to 12.6 degrees F] — that the system could be adapted to sense smaller temperatures changes that could, hypothetically speaking, be then linked to the embryo's sex," Cortez said.

For temperature-dependent sex determination to exist in humans, Graves suggested one possibility is that we somehow become poikilotherms — that is, unable to control our body temperature — much like the naked mole-rat. Another possibility is that instead of live births, we were to somehow lay eggs like a platypus, she added.

Controlling sex

So what might humanity look like if temperature could decide the sex of our offspring? The most important consequence would likely be that it would then be trivial for parents to decide their children's sex, Graves said.

One big risk is the potential for a major imbalance between the sexes in a society.

"Many humans like to decide the sex of their kids," Cortez said. "Sadly, in many places on this planet, the preferred sex would be males. So, if humans could decide the sex of their offspring using a non-complicated technique, like changing their body temperature during a specific week during pregnancy — incubation temperature would have to be changed only during the week when sex is determined — I'm confident this would create many societies biased towards men."

That would be a problem.

"We know that excess of one specific sex in adult populations creates an unbalanced population that has been linked to increased violence, more sexual conflict because is not easy for one sex to get a partner, less parental care, and so on," Cortez added. "So, in other words, a less harmonious society."

One could imagine that governments might intervene to ensure that one sex was not too heavily favored. However, "we might then start to speculate what might happen if the choice of sex might not be up to parents — what forces might interest the state to skew the sex ratio one way or the other," Graves said.

Originally published on Live Science.

If a woman catches COVID-19 during pregnancy, can her baby pick up any immunity to the virus in the womb? Early data hint that the answer is yes, but many questions still remain.

In a new study, published Jan. 29 in the journal JAMA Pediatrics, scientists analyzed blood samples from more than 1,470 pregnant women, 83 of whom tested positive for antibodies for SARS-CoV-2, the coronavirus that causes COVID-19, at the time of delivery. Umbilical cord blood samples from the majority of babies born to these women also tested positive for antibodies, suggesting the babies picked up this passive immunity. 

The number of antibodies passed to the baby largely depended on the type and quantity of antibodies that were present in the mother, and when she caught COVID-19 during pregnancy.

"The longer [the] time between maternal infection and delivery, the greater the antibody transfer," study authors Dr. Karen Puopolo and Dr. Scott Hensley of the University of Pennsylvania Perelman School of Medicine wrote in an email. This correlation held true whether the mother developed symptoms of COVID-19 or remained asymptomatic during her infection.

Related: 20 of the worst epidemics and pandemics in history 

The transferred antibodies may provide protection to the newborn baby, but "work remains to be done to determine what levels and types of antibody are needed to protect newborns from SARS-CoV-2 infection, and how long those antibodies may last in the newborn circulation," the authors said. Another big question is how well the transferred antibodies "neutralize" the coronavirus, meaning block its ability to infect cells, they said.

"It is hopeful to have this data," said Dr. Flor Muñoz-Rivas, an associate professor of pediatric infectious disease at the Baylor College of Medicine in Houston, who was not involved in the study. By studying antibody transfer after natural COVID-19 infection, we can gather hints about whether vaccines given to pregnant people provide similar protection to newborns, she said.

Early findings 

In the new study, the team specifically tested for antibodies that latch onto the coronavirus spike protein, a structure that sticks off the virus's surface; the antibodies the team looked for all target the "receptor-binding domain" (RBD), the part of the spike that binds directly to the receptor, or doorway, into cells. RBD antibodies are the most critical for neutralizing the coronavirus, Live Science previously reported.

But not all RBD antibodies can cross the placenta, Muñoz-Rivas said. That's because the placenta allows only certain antibodies through, using a special receptor and protein that transports antibodies into the organ. Only small, Y-shaped antibodies called immunoglobulin G (IgG) can fit into the receptor, so they alone can reach the fetus and provide immune protection, she said.

Not all the babies got protection: 72 of the 83 babies born to antibody-positive mothers had IgG in their cord blood, and the overall quantity correlated with the IgG concentrations in their mothers' blood. The 11 remaining babies who tested negative for antibodies did so for two reasons. 

Six of the babies' mothers had relatively low IgG levels, suggesting that they were likely "so early in their infection that there had not been time for them to produce and transfer antibody across the placenta," the authors said. Either that, or the mothers simply produced fewer antibodies than average, but this is a less likely scenario, they added. The other five babies' mothers only tested positive for so-called IgM antibodies, which cannot cross the placenta. 

IgM antibodies appear early in an infection and then disappear once the infection clears, Muñoz-Rivas said, so the five moms who only tested positive for IgM were in the very early stages of infection. If IgM antibodies appear in a fetus or newborn, this indicates that the fetus was directly infected with the virus. In this study, no IgM for SARS-CoV-2 was detected in any cord blood samples, meaning no fetus caught COVID-19 while still in the womb. 

However, the study cannot say for sure that SARS-CoV-2 is never transmitted to the fetus before birth, the authors said. 

What does this mean for vaccines? 

While the study shows that IgG antibodies can cross the placenta, scientists still need to determine how well the transferred antibodies protect against infection, the authors said. 

Researchers can test how well antibodies block infection using "neutralization assays" — experiments in which they grow the virus in a dish with antibodies and human cells, to see if the antibodies prevent infection, Live Science previously reported. The authors could also follow up on the babies born with antibodies, to see how long their antibodies persist and if any of the babies later catch COVID-19, Muñoz-Rivas said.

These kinds of studies would provide a benchmark of what to expect after a pregnant person catches COVID-19; the natural immune response could then be compared to what we see in vaccinated mothers and their newborns, Muñoz-Rivas said. 

Right now, both the Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) recommend that only people at high risk of SARS-CoV-2 exposure or high risk of severe illness, due to medical conditions, should consider getting the vaccine during pregnancy and that they should consult with a doctor before receiving one.

With other vaccines given in pregnancy, such as those for tetanus and whooping cough, antibody levels in the newborn drop rapidly by the time the baby is two months old, Muñoz-Rivas wrote in an editorial published Jan. 29 in JAMA Pediatrics. This decline then slows, and the antibody levels continue to fall steadily over the next four to eight months. 

Similarly, for COVID-19 vaccines, the antibodies found in cord blood would be the "starting point," or the peak number of antibodies the baby gets before levels begin to drop, she said. To maximize the number of antibodies passed to the fetus, mothers would likely need to wait until the second trimester to be vaccinated; after about 17 weeks of gestation, the placenta grows big enough to pump a significant number of antibodies to the developing baby, she said. 

Although it's encouraging that maternal vaccines could offer protection to newborns, "for COVID, as best as we know right now, the goal would be to protect the mother," Muñoz-Rivas said. 

Pregnancy increases the risk for severe illness and death from COVID-19, while most newborns who have tested positive have had mild or no symptoms and recovered from the virus, according to the CDC. As with influenza infections, mothers appear especially vulnerable in the third trimester and are more likely to develop severe conditions, like pneumonia and respiratory failure, if they catch COVID-19 at that stage, Muñoz-Rivas said.

So the second trimester might be the best time to get vaccinated, she said. That way, potential side effects could be avoided in the first trimester, when conditions like inflammation and fever can disrupt fetal development, while the immune system would still have plenty of time to ramp up its response before the third trimester. Of course, scientists still need to conduct observational studies and clinical trials to figure out the best time during pregnancy to give the COVID-19 vaccine, Muñoz-Rivas said.

"If we can, in addition to that, protect the baby, that's a bonus," she said. That said, since COVID-19 vaccines won't be available for infants anytime soon, Muñoz-Rivas said that she would consider it a fairly significant bonus.

Originally published on Live Science. 

Humans spend about a third of our lives sleeping, and scientists have long debated why slumber takes up such a huge slice of our time. Now, a new study hints that our main reason for sleeping starts off as one thing, then changes at a surprisingly specific age.

Two leading theories as to why we sleep focus on the brain: One theory says that the brain uses sleep to reorganize the connections between its cells, building electrical networks that support our memory and ability to learn; the other theory says that the brain needs time to clean up the metabolic waste that accumulates throughout the day. Neuroscientists have quibbled over which of these functions is the main reason for sleep, but the new study reveals that the answer may be different for babies and adults.

In the study, published Sep. 18 in the journal Science Advances, researchers use a mathematical model to show that infants spend most of their sleeping hours in "deep sleep," also known as random eye movement (REM) sleep, while their brains rapidly build new connections between cells and grow ever larger. Then, just before toddlers reach age 2-and-a-half, their amount of REM sleep dips dramatically as the brain switches into maintenance mode, mostly using sleep time for cleaning and repair.

Related: 5 surprising sleep discoveries 

"It was definitely shocking to us that this transition was so sharp," from growth mode to maintenance mode, senior author Van Savage, a professor of ecology and evolutionary biology and of computational medicine at the University of California, Los Angeles and the Santa Fe Institute, told Live Science in an email. The researchers also collected data in other mammals — namely rabbits, rats and guinea pigs — and found that their sleep might undergo a similar transformation; however, it's too soon to tell whether these patterns are consistent across many species.

That said, "I think in actuality, it may not be really so sharp" a transition, said Leila Tarokh, a neuroscientist and Group Leader at the University Hospital of Child and Adolescent Psychiatry and Psychotherapy at the University of Bern, who was not involved in the study. The pace of brain development varies widely between individuals, and the researchers had fairly "sparse" data points between the ages of 2 and 3, she said. If they studied individuals through time as they aged, they might find that the transition is less sudden and more smooth, or the age of transition may vary between individuals, she said.

An emerging hypothesis 

In a previous study, published in 2007 in the journal Proceedings of the National Academy of Sciences, Savage and theoretical physicist Geoffrey West found that an animal's brain size and brain metabolic rate accurately predict the amount of time the animal sleeps — more so than the animal's overall body size. In general, big animals with big brains and low brain metabolic rates sleep less than small animals with the opposite features. 

This rule holds up across different species and between members of the same species; for instance, mice sleep more than elephants, and newborn babies sleep more than adult humans. However, knowing that sleep time decreases as brains get bigger, the authors wondered how quickly that change occurs in different animals, and whether that relates to the function of sleep over time.

To begin answering these questions, the researchers pooled existing data on how much humans sleep, compiling several hundred data points from newborn babies and children up to age 15. They also gathered data on brain size and metabolic rate, the density of connections between brain cells, body size and metabolic rate, and the ratio of time spent in REM sleep versus non-REM sleep at different ages; the researchers drew these data points from more than 60 studies, overall. 

Babies sleep about twice as much as adults, and they spend a larger proportion of their sleep time in REM, but there's been a long-standing question as to what function that serves, Tarokh noted.  

Related: From dino brains to thought control — 10 fascinating brain findings

The study authors built a mathematical model to track all these shifting data points through time and see what patterns emerged between them. They found that the metabolic rate of the brain was high during infancy when the organ was building many new connections between cells, and this in turn correlated with more time spent in REM sleep. They concluded that the long hours of REM in infancy support rapid remodeling in the brain, as new networks form and babies pick up new skills. Then, between age 2 and 3, "the connections are not changing nearly as quickly," and the amount of time spent in REM diminishes, Savage said. 

At this time, the metabolic rate of cells in the cerebral cortex — the wrinkled surface of the brain — also changes. In infancy, the metabolic rate is proportional to the number of existing connections between brain cells plus the energy needed to fashion new connections in the network. As the rate of construction slows, the relative metabolic rate slows in turn.  

"In the first few years of life, you see that the brain is making tons of new connections … it's blossoming, and that's why we see all those skills coming on," Tarokh said. Developmental psychologists refer to this as a "critical period" of neuroplasticity — the ability of the brain to forge new connections between its cells. "It's not that plasticity goes away" after that critical period, but the construction of new connections slows significantly, as the new mathematical model suggests, Tarokh said. At the same time, the ratio of non-REM to REM sleep increases, supporting the idea that non-REM is more important to brain maintenance than neuroplasticity.

Looking forward, the authors plan to apply their mathematical model of sleep to other animals, to see whether a similar switch from reorganization to repair occurs early in development, Savage said. 

"Humans are known to be unusual in the amount of brain development that occurs after birth," lead author Junyu Cao, an assistant professor in the Department of Information, Risk, and Operations Management at The University of Texas at Austin, told Live Science in an email. (Cao played a key role in compiling data and performing computations for the report.) "Therefore, it is conceivable that the phase transition described here for humans may occur earlier in other species, possibly even before birth."

In terms of human sleep, Tarokh noted that different patterns of electrical activity, known as oscillations, occur in REM versus non-REM sleep; future studies could reveal whether and how particular oscillations shape the brain as we age, given that the amount of time spent in REM changes, she said. Theoretically, disruptions in these patterns could contribute to developmental disorders that emerge in infancy and early childhood, she added — but again, that's just a hypothesis. 

Originally published on Live Science. 

Mothers with COVID-19 appear unlikely to pass the disease to their newborn babies — even if they breastfeed and share the same room — provided they take certain precautions, a small new study suggests.

The study found that, out of 120 babies born to mothers with COVID-19, none contracted the disease during childbirth or in the two weeks after birth, even though most of the mothers breastfed, had skin-to-skin contact and shared a room with their babies. The mothers took steps to prevent the spread of COVID-19, including wearing surgical masks, and washing their hands and breasts before having contact with and breastfeeding their babies, according to the study, published Thursday (July 23) in the journal The Lancet Child & Adolescent Health.

"We hope our study will provide some reassurance to new mothers that the risk of them passing COVID-19 to their babies is very low," study co-lead author Dr. Christine Salvatore, a pediatric infectious diseases specialist at Weill Cornell Medicine-New York Presbyterian Komansky Children's Hospital in New York City, said in a statement. Still, the authors note that their study was relatively small, so larger studies are needed to confirm the results.

Given that COVID-19 is such a new disease, data on the risks of transmission from mothers to newborns has been limited. There have been several case reports of newborns that tested positive for COVID-19 within 48 hours after birth and appeared to have contracted the disease in the womb, the authors said. But such reports are rare.

Related: Having a Baby: Stages of Pregnancy

Guidance to pregnant women and new mothers with COVID-19 has been in flux. In the beginning of the pandemic, the American Academy of Pediatrics (AAP) initially recommended that mothers with COVID-19 be separated from their newborns, and that babies be fed with expressed breast milk until the mother was no longer infectious. However, the AAP recently updated their guidelines to say that mothers with COVID-19 may share a room and breastfeed with certain precautions. 

The new study analyzed information from mothers who tested positive for COVID-19 and gave birth at one of three New York CIty hospitals between March 22 and May 17. About three-quarters of the mothers reported experiencing symptoms, and of these, about half had symptoms around the time of delivery. 

At the hospital, the mothers were allowed to share a room with their newborns, who were kept in enclosed cribs 6 feet (1.8 meters) away from the mother's bed. Mothers were also allowed to breastfeed if they felt well enough, but were required to wear surgical masks and wash their hands before holding their babies and wash their breasts before breastfeeding.

All of the babies were tested for COVID-19 within the first 24 hours after birth, and none tested positive for the disease. Of the 120 babies, 79 were tested again about a week after birth, and 72 were tested two weeks after birth. Again, none tested positive, nor did they show any symptoms of COVID-19, the report said.

Fifty-three babies had a remote checkup via videoconference at 1 month of age, and all were well and experiencing typical growth. Overall, there was no difference in outcome for babies born to mothers experiencing symptoms versus those born to mothers with COVID-19 who weren't experiencing symptoms, the study found.

"We know that skin-to-skin contact and breastfeeding are important both for mother-infant bonding and for long-term child health. Our findings suggest that babies born to mothers with COVID-19 infection can still benefit from these safely, if appropriate infection control measures are followed," study co-lead author Dr. Patricia DeLaMora, a pediatric infectious diseases specialist at Weill Cornell Medicine-New York Presbyterian Komansky Children's Hospital, said in a statement.

The authors note that about one-third of the 120 babies did not have a follow-up test for COVID-19 after birth, which they say might be due to the parents' fear of going to the doctor (often via public transportation) in the middle of a pandemic. In addition, the researchers were not able to screen the babies' blood, urine or fecal samples for COVID-19 because these types of tests were not approved at the time of the study, they said.

The infants were not tested for antibodies against COVID-19, and whether they could have acquired protective antibodies against the disease from their mothers while in the womb or through breastfeeding is unclear. Because about half of the mothers were symptomatic shortly before or during delivery, it is unlikely that all of the infants could have acquired protective antibodies, the authors said, given that it takes time for the mothers to develop and pass them on.

The new study provides "valuable data indicating that perinatal SARS-CoV-2 transmission is unlikely and allowing newborns to room-in and breastfeed is safe, with appropriate precautions," Dr. Melissa Medvedev, an assistant professor of pediatrics at the University of California San Francisco, who was not involved with the study, wrote in a commentary accompanying the study. (SARS-CoV-2 is the name of the novel coronavirus that causes COVID-19.)

However, many questions about COVID-19 in pregnancy remain unanswered, Medvedev said, such as how often pregnant women or their babies experienced complications from the disease, and how frequently it spreads from mother to child.

Originally published on Live Science. 

A small new study found signs of damage to the placenta in pregnant women with COVID-19, but it's far too early to say whether this damage actually affects birth outcomes. Most women with the novel coronavirus who had these abnormalities gave birth to healthy babies at-term. 

The study researchers examined placentas from 16 pregnant women who tested positive for COVID-19, and found that the placentas contained blood clots and showed signs of abnormal blood flow between mother and baby. 

However, the study does not prove that COVID-19 was behind these abnormalities with the placenta. Indeed, nearly half of pregnant women without COVID-19 who had their placentas examined for other reasons also show such signs of injury. 

In addition, given that most of these women had normal pregnancies and delivered seemingly healthy babies at full-term, it's unclear these placental changes mean much. The researchers note that even partly damaged placentas can often supply babies with sufficient nutrients. 

"Placentas get built with an enormous amount of redundancy," study co-author Dr. Emily Miller, an assistant professor of obstetrics and gynecology at Northwestern University Feinberg School of Medicine in Chicago, said in a statement. "Even with only half of it working, babies are often completely fine."

Still, Miller added "there's a risk that some pregnancies could be compromised." The findings suggest the need to closely monitor pregnant women with COVID-19, the authors concluded.

Such monitoring might include ultrasounds to measure if the baby is growing at a typical rate, and so called non-stress tests that check how well the placenta is delivering oxygen, the researchers said.

However, experts not involved with the study expressed concern that many other diseases in pregnancy could lead to similar injury to the placenta, and so it's too soon to know if these changes were caused by COVID-19.

Related: 5 Reasons Why Placentas Are Amazing 

Signs of injury 

The placenta is a vital structure that supplies oxygen and nutrients to the baby in utero, and removes waste products from the baby's blood, according to The Mayo Clinic. Some viral infections in pregnancy, such as cytomegalovirus and Zika virus, are known to be linked with abnormalities in the placenta, but whether this occurs with coronaviruses is unknown. (These diseases can also lead to problems after birth, such as the microcephaly, or reduced head volume, caused by Zika virus.)

The new study, published May 22 in American Journal of Clinical Pathology, is one of the largest to examine placentas in pregnant women with COVID-19. Among the 16 women in the study, 15 delivered in the third trimester, and one experienced a miscarriage in the second trimester. The researchers don't know whether the miscarriage was related to the woman's COVID-19 infection.

The researchers compared the placentas of these 16 pregnant women with COVID-19 with those of 17,479 women without COVID-19 who required a placental examination, often because they had pregnancy-related conditions, such as preterm birth or preeclampsia. But within this group of "controls" were 125 women who had melanoma. The authors chose to focus on this group in particular because they require placental examination after birth to check for cancer spread; but melanoma itself is not thought to affect pregnancy outcomes.

About 80% of the women with COVID-19 showed a type of placental injury known as "maternal vascular malperfusion," which is a sign of insufficient blood flow between mother and baby due to abnormal blood vessels. In contrast, 27% of women with melanoma and 44% of all controls (women without COVID-19 with and without melanoma) showed this abnormality.

"Our findings indicate a lot of the blood flow was blocked off, and many of the placentas were smaller than they should have been," Miller said.

In women with COVID-19, the researchers also observed "intervillous thrombi," or blood clots in the placenta. This finding fits with research showing that some patients with COVID-19 experience clotting problems, the authors said.

Skepticism 

However, Dr. Kristina Adams Waldorf, a professor of obstetrics and gynecology at the University of Washington School of Medicine, did not find the results convincing. 

"I'm concerned that the scientists that wrote this manuscript have taken a leap from seeing some placental pathology to the conclusion that the virus does in fact cause injury," Adams Waldorf told Live Science. She noted that there are "many many other conditions that can cause a similar profile of placental pathology." This makes it hard to tease out the effects of COVID-19 from other common conditions during pregnancy, such as high blood pressure, obesity and diabetes, she said.

Much larger studies that take into account these common pregnancy conditions are needed to get a better picture of the specific effects of COVID-19 in pregnancy, she said. 

Other studies in lab dishes can look at the effects of the virus on placental cells. Adams Waldorf is currently conducting lab studies to examine the placenta's antiviral immune response to the virus.

In addition, most of the women in the current study contracted COVID-19 late in pregnancy, in the third trimester, but little is known about the effects of the virus early in pregnancy.

The new study also found that, among the 15 live births to women with COVID-19, none of the babies tested positive for the disease. 

One recent study suggested that three babies in China may have contracted the new coronavirus in the womb, in what's known as vertical transmission, but these findings were inconclusive, Live Science previously reported. Overall, evidence so far suggests that vertical transmission is "at most, very rare," the authors of the new study wrote.

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Originally published on Live Science.  

Editor's note: This article was updated on May 4 to clarify statements by study author Dan McCloskey. The original article was published on April 30. 

Naked mole rats are supremely weird creatures — they don't need much oxygen, and instead have seizures if they don't get enough carbon dioxide, the chemical humans exhale when we breathe, researchers just found.The scientists found that the wrinkled rodents will even seek out areas that have been infused with the gas. 

But why? Turns out, due to a genetic mutation, naked mole rats lack an important switch in their brains that helps to tamp down electrical activity in the organ, and thus, prevent seizures, according to a new study published today (April 30) in the journal Current Biology. This mutation might seem dangerous, but in reality, it allows the mole rat to conserve its precious energy stores. Rather than expending energy to operate the anti-seizure switch, the rodents rely on carbon dioxide to keep their brain activity in check. 

"Carbon dioxide is really good at calming the brain down, if not shutting the brain down," said study author Dan McCloskey, an associate professor of psychology at the Graduate Center of The City University of New York. McCloskey studies epilepsy, a neurological condition characterized by recurrent seizures, and thinks the study of naked mole rats could help to unravel mysteries surrounding the human medical condition.

Related: Extreme life on Earth: 8 bizarre creatures

For instance, about 2% to 4% of children under age 5 experience seizures after running a high fever — a phenomenon known as a febrile seizure, according to the medical reference site UpToDate. A 2014 study published in the journal EMBO Reports suggests that some of these children share the same genetic quirk that leaves naked mole rats prone to seizures in the absence of carbon dioxide. 

While more research will be needed to explain this connection, McCloskey said that his mole rat study hints that, in addition to genetics, air quality and breathing patterns may play important roles in human epilepsy.  

It is conceivable that there are "people walking the planet … who are more sensitive to the air around them," McCloskey told Live Science. Further research into what provokes seizures in naked mole rats, and what prevents them, could help guide future studies in human patients, he added. 

An unexpected connection 

So how did McCloskey, a psychology professor, connect the dots between naked mole rats and children with epilepsy?

"It all started with a fact-a-day calendar I got from my sister-in-law," he said. 

On April 17, 2007, the calendar read, "Did you know: The African naked mole rat is neither a mole nor a rat, and is the only cold-blooded mammal," meaning the animal cannot regulate its body temperature physiologically, but varies in temperature depending on its surroundings. Intrigued by the notion, McCloskey wondered if there might be similarities between naked mole rats and human babies and infants, who cannot effectively regulate their body temperatures as adults can. He began studying the quirky creatures shortly after. 

Whereas humans soon outgrow their poor thermoregulation ability, naked mole rats of all ages must move about their nests to maintain an optimum body temperature, retreating deeper underground during the hottest hours of the day and huddling for warmth when necessary, McCloskey and his co-authors noted. 

Related: The 12 weirdest animal discoveries

In addition to seeking out that thermal sweetspot, the rodents spend more than 70% of their time in a so-called nest chamber, where the queen naked mole rat and a breeding male spend most of their time, the authors found. The chamber contains the highest concentration of carbon dioxide in the nest, reaching 2.33% of the total atmospheric pressure, as compared with about 0.5% in nearby food chambers and as little as 0.05% in toilet chambers. The team housed two naked mole rat colonies in their lab and were able to infuse carbon dioxide into different chambers of the nest to see what would happen. The mole rats responded by visiting those areas more frequently and even relocating their primary nest chamber near the infusion site. 

The behavior suggested that naked mole rats not only tolerate high concentrations of carbon dioxide, they actually seek them out. Further research revealed one reason why: the compound might protect the mole rats from seizures.

Carbon dioxide as an anticonvulsant 

When exposed to hot air, heated to about 107 degrees Fahrenheit (42 degrees Celsius), with a low concentration of carbon dioxide, naked mole rats begin to hyperventilate and seize just as infants do during a febrile seizure, the authors found. Many mammals hyperventilate when extremely overheated, as the reflex releases moderate amounts of heat from the body, McCloskey said. Hyperventilating also rids the body of carbon dioxide, which may not be the best thing for naked mole rats.   

While the mole rats suffered seizures in the low-CO2 air, they did not seize when the team used hot air with similar carbon dioxide concentrations (around 2.5%) as those found in the nest chamber. The high-CO2 air even helped suppress seizures in mole rats that had been deprived of carbon dioxide for certain periods of time, as evidenced by measurements of the animals' brain waves. However, some signs of seizure, such as head bobbing and twitchy mouth movements, persisted throughout the experiment. After experiencing a seizure in the low-CO2 air, the mole rats' blood was also less acidic due to the marked loss of carbon dioxide. 

Taken together, these findings suggested that carbon dioxide deprivation, not heat, somehow triggered the rodents' seizures. When the levels of carbon dioxide get low, their blood gets too basic, meaning less acidic, "and that's what causes the seizures," said Thomas Park, a professor and associate department head of Biological Sciences at the University of Illinois at Chicago, who was not involved in the study. 

The big question is why.

To find out, McCloskey teamed up with researchers from the University of Helsinki in Finland, who conducted the 2014 EMBO Reports study. By studying a family with a history of febrile seizures, the Helsinki researchers had spotted a rare mutation in a gene that normally helps regulate brain activity. Upon joining the naked mole rat project, they wondered if the rodents might harbor a similar mutation. Turns out, they share the exact same gene variant.   

When mutated, this gene prompts brain cells to build a faulty version of KCC2, a protein that normally pumps chloride out of cells in response to certain signals. 

Related: The 10 strangest animal stories of 2019

Charged particles such as chloride, which carries a negative charge, move in and out of brain cells in response to various chemicals, known as neurotransmitters. When the balance of negative and positive charges within the cell hits a certain threshold, the brain cell fires off an electrical pulse and sends the signal on to nearby cells. In the adult brain, a neurotransmitter called GABA controls the flow of chloride in and out of neurons and normally works to suppress electrical activity — dampen the ability of  brain cells to fire.  But in very young mammals like human fetuses and premature babies, and newborn rats and mice, things may work a bit differently.  

Baby brains 

Early in development, brain cells contain a far higher concentration of chloride than they do in the adult brain, according to a 2014 report in the journal Nature Reviews Neuroscience. At the same time, these immature brain cells contain very little KCC2, meaning they cannot easily get rid of chloride. That buildup of chloride triggers the neurotransmitter GABA — the chemical that normally suppresses too much neural activity; but in these immature brain cells, GABA might actually promote electrical activity, McCloskey said.  

Basically, naked mole rats seem to maintain "baby brains" throughout their life spans, he said. 

To test this theory, the team investigated how naked mole rats would react to the anti-seizure medication diazepam, which boosts GABA activity in an attempt to calm brain cells. Rather than suppress seizures, though, the drug "rapidly triggered seizures when injected in normal air at room temperature." But in carbon dioxide-rich air of the same temperature, diazepam kicked in as it does in other adult rodents: It put the mole rats to sleep.   

With the help of carbon dioxide, GABA can turn down electrical activity in the mole rat brain, despite their genetic mutation, McCloskey said. 

"They're using the byproduct that we usually consider to be bad and they're using it for good," Park added. A typical KCC2 pump costs ample amounts of energy to run, and given their cramped, underground habitat and limited food supply, naked mole rats don't have much energy to spare. By taking advantage of the carbon dioxide in their nests, rather than constantly using the KCC2 pump, the rodents can save energy while still keeping their brain activity under control, Park said. 

While naked mole rats use carbon dioxide to control their seizures all the time, a similar strategy could help epilepsy patients in the short-term. A 2011 study led by the University of Helsinki suggested that doctors could quickly suppress seizures in epilepsy patients by having them inhale air made up of 5% carbon dioxide. 

More research is needed to determine precisely how the compound interacts with the GABA system, McCloskey said. And naked mole rats may rely on more than carbon dioxide to keep seizures at bay, he added. "We're curious about what other strategies these guys are using" and whether any could translate into humans, he said.

Beyond health care, the study fills in a missing chapter in mole rat evolutionary history, suggesting that the animals' unique social structure may partially stem from the need to control their seizures without expending too much energy. Many other factors drove naked mole rats underground 35 million years ago, and the animals adapted to their new home in increasingly bizarre ways, such as never dying of old age, McCloskey said.  

"All of these factors together make you wonder, 'well, what [adaptations] came first?'" Park said. "It's a mystery because we can't go back ... and observe what happened." 

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Originally published on Live Science. 

Three babies in China may have contracted the new coronavirus in the womb shortly before birth, according to two new reports.

However, experts say the evidence in these cases is inconclusive and does not prove the new coronavirus, SARS-CoV-2, can pass from mother to child during pregnancy.

In one report, doctors from Renmin Hospital of Wuhan University in Wuhan, China, describe the case of a woman who gave birth several weeks after she was hospitalized for COVID-19, the disease caused by the new coronavirus. The baby girl was delivered by cesarean section, and the mother wore an N95 mask and did not hold the infant, according to the report, published today (March 26) in the journal JAMA. The newborn was immediately quarantined, but showed no symptoms.

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Two hours after birth, tests showed the baby had elevated levels of two types of antibodies against SARS-CoV-2. These antibodies are known as IgG and IgM. Although IgG antibodies are known to pass from mother to child during pregnancy, IgM antibodies are too large to cross the placenta, according to an editorial accompanying the report. Thus "detection in a newborn reasonably could be assumed to reflect fetal production following in utero infection," the editorial said.

The infant also had increased levels of immune system chemicals called cytokines, as well as white blood cells, which can be signs of infection. 

But critically, the baby repeatedly tested negative for the SARS-CoV-2 virus itself. This means it's unclear if the baby was ever really infected with the virus, or if there could be another explanation for the positive IgM result.

In a second report, also published in JAMA on March 26, doctors from Zhongnan Hospital of Wuhan University analyzed blood samples from six newborns, looking for antibodies against SARS-CoV-2. They found five infants had elevated levels of IgG, and two infants had elevated levels of IgM, like the baby in the first report. But none of these infants tested positive for SARS-CoV-2.

One explanation besides SARS-CoV-2 infection could be that the mothers' placentas were damaged or abnormal in some way, allowing IgM antibodies to pass through the placenta to the infants, the authors from  Zhongnan Hospital wrote.

It's also important to note that IgM tests can be prone to both false positive and false negative results, and are not typically used to diagnose infections acquired in utero, according to the editorial. 

"Although these two studies deserve careful evaluation, more definitive evidence is needed before the provocative findings they report can be used to counsel pregnant women that their fetuses are at risk from congenital infection with SARS-CoV-2," the editorial concluded.

Earlier this month, a baby in London reportedly tested positive for SARS-CoV-2 minutes after being born to a mother with COVID-19, Live Science previously reported. However, in that case, it's still unclear if the virus passed to the infant during or immediately after birth.

In addition, a preliminary study of nine pregnant women with COVID-19 found no evidence of SARS-CoV-2 passing from mother to child in the womb, Live Science previously reported.

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Originally published on Live Science. 

A newborn in London has tested positive for the novel coronavirus SARS-CoV-2, just minutes after being born to a mother who was also infected with the virus, according to news reports.

Days prior to giving birth, the woman was admitted to a hospital for symptoms of pneumonia, finding out she had tested positive for the virus that causes COVID-19 only after her baby was born at North Middlesex hospital in Enfield, in north London, The Guardian reported.

According to The Sun, the baby was being treated at the hospital, while the mother had been transferred to an infectious-diseases hospital.

It is not known when the child contracted the disease. "We can't say it happened while the baby was still in the womb," Dr. William Schaffner, a professor of Preventive Medicine and Infectious Diseases at the Vanderbilt University School of Medicine, told Live Science. The baby could have also contracted the virus during, or immediately after, birth, Schaffner said.

Some infections pass from a mother to her baby through the mother's placenta, while the fetus is still developing in the womb, or from bodily fluids during delivery. For instance, the Zika virus — which is in another family of viruses from this coronavirus — can pass to newborns both in the womb and during delivery, according to the Centers for Disease Control and Prevention (CDC). When passed to a baby in the womb, the Zika virus can cause microcephaly and other severe brain defects, the CDC said. 

"That was a terrible phenomenon that happened with Zika," Schaffner said.

The first known newborn who tested positive for SARS-CoV-2 did so within 36 hours of birth. In that case, it also wasn't clear whether transmission happened in the womb. 

Following that news, researchers analyzed samples from nine women who came down with COVID-19 when they were 36 to 39 weeks pregnant, and were admitted to a hospital in Wuhan, China, where the outbreak began. All of the women delivered via C-section. To find out if and perhaps when the virus could be transmitted, the team looked at samples of amniotic fluid, umbilical cord blood, breast milk and samples from the newborn's throat. 

None of those samples tested positive for the coronavirus, and both the mothers and babies survived, according to that study, published Feb. 12 in the journal The Lancet. In those cases, at least, the virus didn't appear to pass between a mother and her developing fetus.

Right now, the bigger question is how the baby will fare.

"Does the baby become sick?" Schaffner asked. "Does the baby also develop pneumonia?"

Children infected with this coronavirus are mostly showing mild symptoms. But there isn't enough data yet to say whether babies would fall into this category.

"Newborns are particularly vulnerable, and they may be exceptions to that general rule since they are so vulnerable," Schaffner said.

As the coronavirus spreads across the globe, everyday life is being transformed with social-distancing measures, school closures, event cancellations, and in some cases, entire city lockdowns.

Though pregnant women tend to be at a higher risk of catching some respiratory infections and developing more severe symptoms from those infections, that doesn't seem to be the case for the coronavirus, according to a report published at the end of February by the World Health Organization-China Joint Mission on Coronavirus Disease 2019. Of 147 pregnant women with either confirmed or suspected cases of COVID-19, only 8% had a severe form of the disease and just 1% were in critical condition, according to that report.

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Originally published on Live Science. 

If you have a baby, you may be worried about them catching the coronavirus, particularly after media reports of an Australian infant diagnosed with it.

The good news is, the evidence so far is babies almost never get seriously ill from the coronavirus. And even if infected, they may have no symptoms.

However, the coronavirus could affect infants in other ways. For instance, there may be difficulties accessing health care, consumer goods and child care.

Thinking about these possibilities now, and preparing for them, can help you manage what may come.

Related: The ultimate kids' guide to the new coronavirus

Health care access may be tricky, but there are ways

If the coronavirus becomes widespread, the health system will struggle to cope for a while.

Up to 20% of people who get COVID-19 need treatment in hospital for up to two weeks or more.

Hospitals and general practices may be overwhelmed by others sick with the coronavirus, which may make it difficult to access health care if your baby gets sick for any reason.

Recognizing this, the Australian government recently announced special provisions for parents of newborns to be bulk-billed when consulting a doctor or nurse via phone or videocall rather than in person.

There are also things you can do to help keep your baby healthy so they don’t need medical treatment. By protecting them, you also protect the people around them who may be more vulnerable to serious illness from the coronavirus.

Think about hygiene

The first thing you can do is to practice good hygiene yourself. This includes frequently washing your hands, avoiding close contact with other people as much as you can, coughing or sneezing into your bent elbow or a tissue, and avoiding touching your eyes, nose and mouth.

Because babies put their hands in their mouths no matter what, frequently washing their face and hands and cleaning surfaces and objects they might touch will help protect them from any infection.

How about daycare?

It will come as no surprise to most parents that babies who attend daycare are sick more often.

That’s because babies and small children have an immature immune system, are in very close contact with one another, and may end up sharing saliva with one another by mouthing and touching one another and the same toys.

So, if you can, keep your baby away from daycare. However, if you need to use it, when you pick up your baby from daycare, wash their hands and face, change their clothes, then wash your own hands, before scooping them into that big, warm hug.

Make sure vaccinations are up to date

Routine vaccination is the safest, most effective way to protect babies and children from illness.

So, keep your child's vaccinations up-to-date to minimize the chance they'll need medical attention while the health system is dealing with the coronavirus.

If you're breastfeeding

Breast milk contains many ingredients to help prevent and fight infection. It is recommended babies be fed only breast milk until they are 6 months old and continue breastfeeding with other foods into their second year of life.

If your baby is under 6 months and breastfeeding, offering them only breast milk protects them from a range of infections and reduces their need for medical treatment or hospitalization.

If your baby is breastfeeding and using formula, consider replacing formula feeds with breastfeeds.

If you have stopped breastfeeding altogether, it is possible to start breastfeeding again if you want to (contact the national Breastfeeding Helpline for assistance).

If you have an older baby or toddler who is still breastfeeding, keeping breastfeeding will help protect them from other illnesses until after the coronavirus pandemic has passed.

If you're using formula

It is easy to accidentally introduce germs into bottles while you're preparing infant formula. So, because medical care may be hard to access, it is worth taking extra care to prevent this.

Shop for supplies, such as nappies

Supply chains may be disrupted if lots of people get ill. And you may not be able to shop if you need to self-isolate at home.

It is recommended you have two to three weeks worth of supplies at home to prepare for this possibility. Consider stocking up on nappies for this length of time, or keeping washable (cloth) nappies on hand.

If you are formula feeding, buy enough infant formula for three weeks but check the expiry dates.

What if mum contracts the coronavirus?

Mothers are more at risk of becoming sick from the coronavirus than their babies.

And if you're breastfeeding and you're infected, it is recommended you continue breastfeeding. That’s because the virus has not been found in breastmilk.

Wearing a mask when you are with your baby (including during feeding), washing hands before and after contact with your baby, and cleaning and disinfecting surfaces and any feeding equipment will help prevent your baby catching the virus from you.

If you are are hospitalized or separated from your baby, you can express breastmilk for them.

Think about keeping grandparents safe

If you or your partner get ill, someone else may need to help care for the baby or other children.

Babies like to share their saliva with their caregivers and they may be infected with the coronavirus but have no symptoms. So they may easily spread the infection to the people looking after them.

Many parents call on grandparents to help with child care. Unfortunately people over 60 are the most likely to get seriously ill or die from the coronavirus.

So, if your standby carers are over 60, now is the time to think about making alternate childcare arrangements.

Talk with grandparents about how they can reduce their risk of infection if they need to look after the baby.

[ Deep knowledge, daily. Sign up for The Conversation's newsletter. ]

This article was originally published at The Conversation. The publication contributed the article to Live Science's Expert Voices: Op-Ed & Insights.

You might find yourself hiccuping after a holiday meal or a glass of wine — or sometimes just out of the blue. But is there a purpose to these repeated "hics"?

Exactly why humans hiccup is a mystery, but scientists do have one intriguing theory —  hiccupping may help a fetus in utero learn to breathe. Later in life, hiccupping is a vestige of that early respiratory training.

In other words, hiccups are essentially useless in adults, said Dr. Peter Kahrilas, a professor of gastroenterology and hepatology at Northwestern University’s Feinberg School of Medicine in Chicago. 

Hiccups are a reflex, analogous to the jerk reflex produced when a doctor hits your knee with a hammer. When the reflex is triggered, most often by stimulation to the esophagus or stomach, the brainstem sends signals to the diaphragm and other respiratory muscles, causing them to involuntarily contract, which results in a sudden intake of air. Then the epiglottis (a flap of tissue behind the tongue) flips over, as it does during swallowing, covering the airway and causing the hiccup's characteristic sound. 

Related: 11 Surprising Facts About the Respiratory System

Because hiccupping closes the airway, it has no respiratory function, nor other obvious use in adults, Kahrilas said. Unlike, say, the gag reflex, which prevents choking, the reflex to hiccup doesn't protect the airway or throat. "It serves no function whatever," said Kahrilas of the hiccup reflex in adults. "In essence, what you're doing is you're, stimulating inspiration, but then you're preventing inspiration. And then it happens repetitively, which is what we all know about the hiccups," Kahrilas added. 

However, the situation is different in utero and in newborns. In utero, the fetus gets oxygen through the placenta, but as soon as the baby is born, his or her life depends on being able to breathe, Kahrilas explained. "You have to have a breathing apparatus that is already trained," he said. Kahrilas suggests that hiccups, which begin in utero, provide that training by repetitively causing the breathing muscles to contract. "It's almost like an isometric exercise … you're trying to inhale, but then you're closing the [airway], so that it makes it harder to inhale," Kahrilas said.

It's an exercise that fetuses in utero and neonates do a lot. Preterm infants spend an estimated 1% of their time (about 14 minutes per day) hiccupping, according to a recent study in Clinical Neurophysiology that examined the brain activity associated with hiccupping in preemies. Researchers have recorded hiccupping in the womb as early as nine weeks into gestation, said Lorenzo Fabrizi, a senior research fellow in the department of neuroscience, physiology and pharmacology at University College London, who led the study.   

Fabrizi and his colleagues monitored 217 preterm and full-term newborns (preterm babies are born before 37 weeks of pregnancy and full-term babies are born after 39 weeks) for hiccupping while also recording the babies' brain activity (through EEG recordings) for about an hour. During that time, the researchers observed  13 infants undergoing a bout of hiccups noting that the hiccups stimulated three different types of brainwaves in the cortexes of the neonates, Fabrizi said.

Previous studies of both animal models and humans, have found that involuntary muscle contractions in utero send signals to the cortex, Fabrizi said. Researchers have proposed that this process teaches the brain where these body parts are so that it can later control them at will, Fabrizi said, and he thinks something similar may be going on with hiccups in newborns.   

"We know that involuntary muscle contraction, in animal studies, allows the brain to form a 'body map'. So, extrapolating this information, then, a potential explanation of what the diaphragm contraction does is to allow the brain to form a map of the respiratory apparatus so that it can be controlled later on," Fabrizi said. 

Human breathing is involuntary most of the time, and depends on signals from the brainstem to the respiratory muscles; but we can also choose to breathe (for instance, when the doctor tells us to "take a deep breath"). It's the ability to control breathing that babies may learn through hiccupping, Fabrizi said. Whether the cortical area stimulated by hiccups is involved in breathing at will is not yet known, he added.

Regardless of the initial function of hiccups, it seems to researchers that hiccups have no use after the neonatal period. 

Still, "the neural circuitry for [hiccuping] persists and it's buried in the brainstem, and it can get activated almost coincidentally or accidentally by any number of stimuli," Kahrilas said. 

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•  Why Do Babies Kick in the Womb? 

Originally published on Live Science. 

Will parents soon have the power to decide how tall or intelligent their children will be? 

Probably not, new research suggests. 

Ethical debate surrounds the concept of so-called "designer babies" — offspring whose embryos are either selected for certain traits or genetically engineered to boast chosen genetic traits. Once the stuff of science fiction, designer babies have become a feasible reality, as one rogue scientist recently demonstrated by creating the world's first gene-edited babies. 

Although gene-editing generates a lot of buzz, a new study, published today (Nov. 21) in the journal Cell, highlights an alternate technique for generating designer babies: selecting "superior" embryos by first screening their DNA. 

Clinicians already use a technique called "preimplantation genetic testing" (PGT) to screen embryos that are generated through in vitro fertilization (IVF) — a procedure where doctors combine parents' sex cells in the lab and later implant the resulting embryo into a person's uterus. Clinicians use PGT to spot genetic mutations that could lead to disease, but potentially, the same procedure could be used to cherry-pick desirable traits like height and intellect.        

Besides the ethical dilemmas, the idea of selecting "optimal" embryos based on their genes has one key flaw: No one knows if it would actually work. 

Related: How to Speak Genetics: A Glossary

"People can argue if it's a good idea or bad idea, but … people didn't really know whether it was going to work or not," said co-author Shai Carmi, whose lab studies statistical and population genetics at The Hebrew University of Jerusalem. Carmi and his colleagues used a combination of genetic data, computer models and real-world case studies to investigate whether scientists could really use PGT to ensure that a given child would grow to be incredibly tall or especially smart. 

Turns out, the science just isn't there yet. 

"If we look at the snapshot of what we can achieve today with the current technology … the gains are rather limited, in particular for IQ," Carmi said. According to the team's models, in the best-case scenario, embryos screened for height-enhancing genes may gain only about 1.2 inches (3 centimeters) of height on average. Embryos screened for intellect may  gain only about 3.0 IQ points, on average. In reality, the benefits would likely be less substantial, and none could be guaranteed.        

In other words, a designer baby's IQ could "end up being much lower or much higher than what is expected," Carmi said. 

"A lot of uncertainty" 

To reach their conclusions, Carmi and his co-authors gathered complete sets of DNA from real people and paired each person's DNA with another's. These "pairs" acted as imaginary couples for their computer model. They then crafted 10 virtual embryos by combining each couple's DNA and screened the embryos for genes linked to height and cognitive ability.

A myriad of genes affect how tall and how bright a given person will be, Carmi said. In previous studies, scientists pinpointed these special DNA segments by poring over the genomes of hundreds of thousands of individuals. The researchers then condensed the mountain of data into "polygenic scores," a metric that tallies how much influence different genes hold over a particular trait.     

They calculated two polygenic scores for their imaginary embryos:  for height and IQ. For each fictional couple, the team selected the top-ranking embryo for each trait — theoretically, the top embryos should produce the tallest and smartest kiddos, they predicted. 

But the difference between the "best" and "worst" scoring embryos proved to be relatively small.  

"The conclusion is that the embryos aren't that different from each other," said Dr. Sinem Karipcin, a fertility specialist and director of the program for preventing genetic diseases at the Columbia University Fertility Center, who was not involved in the study. Given that each set of 10 embryos stemmed from the same imaginary parents, the lack of genetic diversity is not that surprising, Karipcin said. Two sets of DNA can only combine in so many ways, and the same limitation would apply to real parents trying to select designer embryos. 

Related: 5 Myths About Fertility Treatments | IVF & Test Tube Babies  

What's more, polygenic scores for height and IQ may not be very useful for predicting a person's actual height and intelligence, Carmi said. Using 28 families as a case study, the authors applied their computer model to real parents and their grown-up children. With each family's genetic data, the team made predictions as to which child should be tallest, then checked their work against each sibling's true heights. 

"We saw that [the top-ranking] child is indeed taller than the average … but we also see that there's a lot of uncertainty," Carmi said. In some families, the top-ranking child stood about 4 inches (10 centimeters) taller than the average sibling. In others, the top-ranking child fell well below average height. 

Even in their simulated models, the researchers found that a designer baby's true height may vary by about 2 to 4 inches (5-10 cm) from the predicted value. IQ could vary by nearly 20 points in either direction.

The true value of genetic screening 

Beyond the inherent uncertainty of genetics, other factors cloud the predictive accuracy of polygenic scores for height and IQ, the authors noted. Environmental conditions, such as nutrition and upbringing, also shape children's physical and cognitive development and can't be captured through genetic screening. Polygenic scores are overwhelmingly based on European DNA, meaning the metric may hold little value for people of other ancestries, Karipcin said. In their study, the authors also worked with an unusually high number of embryos, she added. 

A young couple may produce five to eight embryos through IVF, granting clinicians options to work with, Karipcin said. But after age 35, a mother may be able to produce only one or two viable embryos through the procedure, she said. Besides being few in number, about 40% of the 35-year-old's embryos may contain an abnormal number of chromosomes. Chromosomes package DNA into X-shaped bundles, and humans usually carry 23 pairs of these structures per cell. In most cases, people can’t survive with an abnormal number of chromosomes — those who do survive are born with developmental disorders, such as Down syndrome or Turner syndrome, according to the University of Utah.         

By the time the potential mother reaches age 43, about 90% of her IVF embryos may bear too many or too few chromosomes, Karipcin said. 

At that point, ranking the handful of embryos for height or intelligence would likely be a fruitless exercise. Even if this biological constraint didn't exist, Karipcin said, she doubts that many parents would opt to use genetic testing to customize their children's looks and abilities. Parents seem more concerned about ensuring that their children grow up healthy and unscathed by disease, rather than incredibly tall, she said.

Related: Future of Fertility Treatment: 7 Ways Baby-Making Could Change

Karipcin regularly uses PGT to screen embryos for genetic quirks, such as single-gene mutations or extra chromosomes, and can reliably predict if a given embryo may develop into a child with Down syndrome, cystic fibrosis, muscular dystrophy or Fragile X syndrome. The hopeful parents also undergo genetic testing to see whether they carry any heritable diseases that they could pass on to their children. 

"If both parents are carriers, [PGT] is the only way to guarantee that they will not transmit the disease to their children," Carmi confirmed. So, while parents can't yet customize their child's height, they could use genetic screening to improve their future health. 

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Originally published on Live Science. 

Babies and young children drank from clay "sippy cups" during the Bronze Age and the Iron Age, and the practice may have existed as early as 7,000 years ago, a new study reveals.

These spouted artifacts have been found at archaeological sites across Europe, first appearing in the Neolithic period and becoming more common, according to the study. Scientists suspected that the vessels were meant for feeding babies and toddlers, but some researchers argued that the pottery may have been meant for adults who were sick, injured or elderly. 

To settle that question, the study authors analyzed vessels from children's graves in what is now Germany to identify what they once held. The researchers found residue of animal milk fats, suggesting that the vessels held milk that was fed to young children to supplement breastfeeding or to help with weaning. 

This is the first "direct evidence of the foods these babies were fed," said lead study author Julie Dunne, a senior research associate with the University of Bristol's School of Chemistry, in the United Kingdom.

Related: Back to the Stone Age: 17 Key Milestones in Paleolithic Life

The researchers examined three vessels from the graves of very young children; the eldest was no more than 6 years old, according to the study. Two of the graves were in a cemetery dating from 800 B.C. to 450 B.C. , and one grave — a cremation burial — was found in a necropolis dating from 1200 B.C. to 800 B.C..

Archaeologists typically look for ancient organic residues by grinding up small pieces of broken pottery — there are often thousands at any given site — and then chemically analyzing the powder, Dunne told Live Science. 

"Based on various molecular and isotopic information, we can tell what kind of products were in the vessel: animal products — meat or milk — plants or beeswax, which would denote honey," she said.

However, testing small, whole objects without damaging them is a lot trickier, Dunne added. For the study, the scientists carefully swabbed the insides of the vessels, collecting grains of loose powder. Fatty acids in the residue from the younger vessels hinted that their milk came from ruminants — animals that chew their cud, such as cows, sheep or goats. The older cup held milk that came from nonruminants, perhaps human or pig milk, the study authors reported.

But could a child have comfortably used one of those cups? To find out, the researchers reconstructed one of the vessels in the study, filled it with diluted applesauce and handed it to an eager 1-year-old.

"He cupped it in his hands and started suckling from it — and he loved it," Dunne told Live Science. "There's something intuitive for a baby about the shape; they all have the same basic shape that you'd hold in between your hands." 

If these cups from the Bronze Age and Iron Age were used to feed babies, it's likely that the same is true for similar cups found at other sites that date to the Neolithic, according to the study.

These cups offer an intriguing glimpse of an important shift in human history. As people transitioned from hunter-gatherer lifestyles to more agrarian habits, they gained reliable access to milk and cereals to feed their babies, which meant families could grow more quickly, Dunne said.

"Hunter-gatherers tend to have gaps of about five years between babies," she noted. "But once people start living an agricultural lifestyle, the inter-birth interval becomes much shorter, more like two years. 

"People have more babies because it's easier to feed them," Dunne added. "Eventually, this leads to people living in larger settlements — and eventually to urbanization." 

The findings were published online Sept. 25 in the journal Nature.

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Originally published on Live Science.

An increasing number of parents are concerned about vaccinating their children, questioning doctors about the necessity and safety of following the immunization schedule recommended by the Centers for Disease Control and Prevention (CDC). However, decades of studies have demonstrated that vaccines are safe and that administering vaccines according to CDC guidelines is critical for building immunity in young bodies, experts told Live Science.

Parents worried about vaccines tend to ask similar questions, said Dr. Robert Jacobson, a physician in pediatric and adolescent medicine with the Mayo Clinic in Minnesota. They want to know if it's more painful to get three or four shots at once, if the baby's immune system can tolerate multiple vaccines, and what might happen if the vaccines are delayed. 

"Other issues are distrust in the health system [and] the government," said Heidi Larson, an anthropologist with the London School of Hygiene and Tropical Medicine and the director of the Vaccine Confidence Project, which studies people's views on immunization. 

These fears may prompt parents to eliminate or delay vaccinations, but such a course can jeopardize an infant's health and raise their risk of contracting a preventable and potentially life-threatening disease, according to the CDC. 

Related: Can You Still Get the Measles If You've Been Vaccinated?

Is it really more painful for babies to get multiple shots in one visit? No — on the contrary, studies have found that infants experience more pain when distressing medical procedures are spread out over several days, compared to when multiple procedures are performed on the same day, Jacobson said. 

In newborns exposed to multiple heel lances — blood collection through puncture — over the course of several days, the drawn-out, painful interventions heightened anxiety and anticipation of pain, researchers reported in 2002 in the journal JAMA.Those babies "learned to anticipate pain and exhibited more intense pain responses" during procedures than infants who did not receive repeated jabs.  

As for multiple vaccines, the recommended combinations do not overwhelm, weaken or "use up" babies' immune systems, as some parents fear; in fact, the multiple shots ultimately strengthen a baby's natural resistance to pathogens, researchers reported in 2002 in a study published in the journal Pediatrics.

"Young infants have an enormous capacity to respond to multiple vaccines, as well as to the many other challenges present in the environment," the scientists wrote in the 2002 Pediatrics study. "By providing protection against a number of bacterial and viral pathogens, vaccines prevent the 'weakening' of the immune system and [the] consequent secondary bacterial infections occasionally caused by natural infection."

A race against time

As for putting off scheduled immunizations, waiting to give vaccines may actually be dangerous to a baby's health.

Such delays can be risky because children need a given vaccine before their first encounter with the disease, Jacobson said. "If this schedule is designed as a race against time to protect the child before they're exposed, the delayed schedule actually increase[s] the chance the child will get the illness before they get the vaccine," he said.

Adding time between doses could mean some vaccines are given too close in time to other scheduled vaccines, so the child's immune system may not respond to either vaccine and will instead ignore them completely. This could cancel out the effectiveness of both immunizations, leaving the child vulnerable to illness.

When vaccinating babies and young children, timing is critical, Jacobson said. For example, a baby may get some immunity against the flu from its mother; a flu vaccine won't work until that protection fades. Other vaccines, such as the inoculation for rotavirus, cannot be given after a child reaches a certain age. Infants get two or three doses of rotavirus vaccine, but after babies reach 8 months old, these vaccines carry an increased risk of a condition called intussusception, when one segment of the intestine "telescopes" inside another segment, potentially leading to an obstruction.

What's more, when parents opt for a delayed vaccination schedule, they rarely follow it. In children born in Portland, Oregon, between 2003 and 2009, only about 1% of parents who postponed their children's vaccines actually followed the altered schedule, according to a study published in 2012 in the journal Pediatrics. 

"It's hard work bringing your children in repeatedly to doctors' visits," Jacobson said. "Everything from scheduling to parking makes it even more complicated, and your children's own lives and your own lives get in the way."

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Originally published on Live Science.

The first weeks and months of a baby's life are full of big changes. But what new parents may not have expected are the tiny hairs left on their newborn's mattress. After a few months, their baby's once-full head of hair has become thin and patchy — or nearly bald. 

Fortunately, infant hair loss is rarely a concern. A fetus starts growing hair during the first trimester. But whether an infant is born with a layer of fuzz or a thick mop, all lose at least some hair. In fact, hair loss simply means an infant is making the huge adjustment to life outside the womb.

On an adult's head, each strand of hair goes through a phase when it's growing and when it's not — and when hair isn't growing, it can also shed. At any given time, only a small percentage of your hair is in this latter stage, and only about 50 to 100 strands are lost per day. Not so for a newborn.

Related: Why Don't Newborns Have Tears or Sweat?

"Big hormonal shifts happen in a baby's body after they are born, which can cause all of their hairs to enter the resting phase at the same time," explained Sage Timberline, a pediatrician at the University of California, Davis, Children's Hospital in Sacramento, California. That means all of a baby's hair can shed at once.

Both mother and baby undergo huge hormonal shifts during labor, which is necessary for a successful birth. The onset of labor alerts a baby's body to start producing hormones that are crucial for life outside the womb. Some hormones help the baby's arteries and veins develop, ensuring that the organs receive ample blood during labor and after the umbilical cord is cut, Timberline told Live Science.

One hormone, called cortisol, helps babies' lungs mature, enabling them to take their first breath, Timberline said. It also helps the baby's body produce its own energy and heat. In adults, cortisol plays a role in a vast array of physiological functions, from regulating metabolism to triggering your "fight-or-flight" response. It's considered the stress hormone, and during times of stress, cortisol helps direct energy toward vital functions and away from less important tasks.

"Labor puts a good kind of stress on a baby," Timberline said. The stress triggers cortisol production, which channels energy toward the developmental changes crucial for survival — and away from nonessential functions such as hair growth. 

Hair today, gone tomorrow

After birth, all of a baby's hair stays in the resting phase until more resources become available. Hair usually starts to shed at 8 to 12 weeks of age, and begins to grow back at around 3 to 7 months. But it's not until around 2 years of age that thicker hair emerges. The specific timing and pattern of hair loss and growth depends on a number of factors, including sex, ethnicity, genetics, the conditions of birth (premature, early or late; or vaginally or by cesarean section), and a baby's nutrition. 

And no, what you may have heard about shaving a baby's head to allow hair to grow back thicker isn't true. The ends of a baby's hair are tapered, and cutting them just leaves them truncated and temporarily looking darker and thicker. 

In fact, the number and location of individual hair follicles are genetically determined, said Katie Ellgass, a pediatrician at Stanford Children's Health Altos Pediatric Associates in Los Altos, California. Once born, a baby doesn't form any new follicles. 

A baby's hair color and texture can also change several times during the first few months or years. But it's hard to predict how and when, Timberline said. "All we can do is enjoy each hairstyle while it lasts," she said, "and don't get too attached!"

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Originally published on Live Science.

Upon entering the world, a newborn lets out a loud, distinct cry — a sign of health and vigor. It's a cry that new parents will quickly become used to in the coming days and weeks. But if you look closely, you'll see that a newborn's cry is a bit different from an older infant's: there are no tears.

Tears, of course, are necessary to protect the eyes and keep them moist. When faced with extreme emotions such as sadness, anger or even happiness, we cry, said Sage Timberline, a pediatrician at the University of California, Davis, Children's Hospital in Sacramento, California. That temporary stress triggers a fight-or-flight response, which produces tears to further protect the eye. These emotional tears can also help release stress-inducing hormones that may have been building up during tough times; this contributes to that sense of relief that follows a good cry, she told Live Science.

While a baby is born with tear ducts, they're not fully developed yet. They produce enough tears to coat the eye and keep it moist, but not enough to form drops that trickle down those chubby cheeks. After three or four weeks, a baby's tear ducts usually mature enough to form teardrops associated with strong emotions, Timberline said.

Related: Why Do Babies Cry on Airplanes?

A newborn's eyes tend to be dry — and so does its skin. No matter how hot it gets, a newborn hardly sweats for the first couple weeks of its life. That's because the sweat glands aren't yet fully functional.

Humans have two types of sweat glands, called eccrine and apocrine glands, both of which are formed in newborns even if they're not yet producing sweat. Apocrine glands secrete sweat through hair follicles but aren't activated until hormonal changes take place during puberty. While apocrine sweat is odorless at first, it can become smelly. It's filled with water and electrolytes as well as steroids, lipids and proteins — which bacteria can process to produce odors.

Eccrine glands start to form during the fourth month of gestation, appearing first on the fetus's palms and on the soles of its feet. By the fifth month, eccrine glands cover almost the entire body. 

After a baby is born, the most active eccrine glands are the ones on the forehead, Timberline said. Soon after, an infant starts sweating on his or her torso and limbs.

Because newborns can't fully sweat, they rely on caregivers to keep them cool. Watch out for signs of overheating, including sweating (since newborns do produce some sweat); warm, flushed skin; rapid breathing; fussiness; and decreased activity of arms and legs, Timberline said. If your baby is too warm, just remove a layer of clothing or use a fan to keep the air circulating.

But once those glands start pumping out sweat, some parents worry that their babies sweat too much when feeding or sleeping, said Katie Ellgass, a pediatrician at Stanford Children's Health Altos Pediatric Associates in Los Altos, California. "Both actions are tough work," she told Live Science. "When feeding, a baby is often close to their caregiver, so body heat is transferring. It's a sweatfest!"

Fortunately, sweaty babies are usually not a concern, Ellgass said. Babies are screened for metabolic diseases and newborn heart problems, so as long as they're gaining weight, baby sweat is … well, nothing to sweat about.

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Originally published on Live Science.

Parents in Spain started panicking this summer when 17 children and babies mysteriously came down with hypertrichosis, or "werewolf syndrome," a condition in which their bodies and faces became covered in a dense layer of hair, according to news reports.

"My boy's forehead, cheeks, arms, legs and hands filled with hair. He had an adult's eyebrow," Ángela Selles, the mother of 6-month-old baby Uriel, told the Spanish newspaper El Pais. "It was very scary because we didn't know what was happening," Selles said.

At first, parents and doctors couldn't figure out what was wrong. Was it genetic? A metabolic disorder? On Wednesday (Aug. 28), the Spanish Health Ministry finally announced that it had discovered the root of the problem. In a pharmaceutical mix-up, babies across Spain had been inadvertently dosed with a medication for alopecia, or hair loss. 

Related: 10 Medical Conditions That Sound Fake But Are Actually Real

All the affected children had one thing in common: They were all taking the same medicated formula that supposedly contained omeprazole, a drug used to treat acid reflux disorders. Early in July, the drug was identified as a suspected culprit for the condition and pulled from the shelves. A later investigation by Spain's Agency for Medicines and Health Products (AEMPS) revealed that instead of omeprazole, the formula the babies were drinking contained minoxidil, a drug used to stimulate hair growth. 

The mix-up happened when, at some point in the packaging process, the medication was mislabeled as omeprazole. By Aug. 6, 22 batches of the tainted formula had been recalled. On Tuesday (Aug. 27), the factory where the drug was produced closed down, El Pais reported. 

Hypertrichosis  is typically associated with an extremely rare genetic condition in which excessive hair growth begins in infancy and persists into adulthood. Only about 50 cases of this kind of hypertrichosis have ever been documented, according to JAMA Dermatology. 

Unlike people with genetic hypertrichosis, however, the babies affected by the mislabeled drug won't always be hairy — the excess hair should begin to fall out after a few months. Still, it's been an ordeal for the parents, who spent weeks shuttling their kids to specialists, and for older kids who were teased at school for their unusual appearance, The Telegraph reported. In addition, at least one child developed liver damage as a result of the mix-up, El Pais reported.

Four families are now preparing to launch a lawsuit against FarmaQuimica Sur, the company behind the mixup.

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 Originally published on Live Science. 

When Lilliya Konovalova became pregnant with twins, she didn't expect to give birth twice. But the 29-year-old, who lives in Northern Kazakhstan, was in the hospital two times — once in May, for the birth of her daughter, and again earlier this month, for the birth of her son. 

"My son was in no rush to come out into the world," Konovalova said, as reported by the Daily Mail. 

The twins were born 11 weeks apart. Such a long interval between twins is rare, but not unheard of. (The world record — twins born 87 days apart — was set in 2012). But it's not just the separate birthdays that set these twins apart — it's the fact that each one gestated in a separate womb. 

That's because Konovalova has a condition called uterus didelphys, which essentially means that she has a double uterus. 

Related: Blossoming Body: 8 Odd Changes That Happen During Pregnancy

Uterus didelphys is surprisingly common — one in 2,000 women have it. The conditions occur early in development, when the two tubes that all female fetuses have, which normally fuse into one uterus, instead develop into two separate wombs. But the odds of a pregnancy like Konovalova's, where each baby develops in its own womb, are miniscule — just one in 50 million, Scientific American reported. (For a woman with uterus didelphys, the odds of conceiving one twin in each are 1 in 25,000).

Similar pregnancies have been documented. In 2009, a woman in Michigan with uterus didelphys delivered two baby girls, one from each side. In 2014, a woman in the United Kingdom with the same condition gave birth to triplets, two of whom shared a uterus, and one of which had its own. 

But in none of these documented cases were the babies born on separate occasions. That means Konovalova's pregnancy was rare on two counts. 

Occasionally, after delivering one twin, a woman's contractions will subside. Sometimes, when the first-delivered twin is extremely premature, doctors will let the second fetus gestate in the mom's womb until it's closer to term, The Washington Post reported. That's what happened to Konovalova. When her daughter Liya was born, Konovalova was only 25 weeks into her pregnancy —  barely past the threshold at which a baby can survive outside of its mother. By the time her son Maxim was born, he'd had much longer to develop inside the womb. 

Konovalova and her twins are both healthy, and getting ready to leave the hospital as a family. 

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Originally published on Live Science.

When babies pass through the mother's birth canal, the tight fit temporarily squashes their wee heads, elongating their flexible skulls and changing the shape of their brains. Now, scientists have created 3D images that demonstrate the extent of that amazing conehead-like distortion.

Babies' heads can change shape under pressure because the bones in their skulls haven't fused together yet, according to the Mayo Clinic. Soft regions at the top of the head accommodate being squeezed through the birth canal and allow room for the brain to grow during infancy.

However, the precise mechanics of how a baby's skull and brain change shape during labor are not well understood. To learn more about that process, scientists conducted magnetic resonance imaging (MRI) scans of seven pregnant women: when the subjects were between weeks 36 and 39 of their pregnancies, and then when they were undergoing labor, after their cervixes were fully dilated. [7 Baby Myths Debunked]

Their images revealed significant skull squeezing — known as fetal head molding — in all the infants, and suggested that the pressures exerted on infant heads and brains during birth are stronger than once thought, scientists reported in a new study.

In all seven fetuses, skull bones that did not overlap prior to labor were visibly overlapped once labor began, deforming the infants' heads and brains, the researchers wrote. In five babies, the skulls returned to their prelabor shapes soon after birth, and the deformation was not noticeable when the newborns were examined.

The MRI scans captured views of soft tissues that were not visible with ultrasound, providing important clues for understanding the deformation of fetal skulls and brains, and the movement of maternal soft tissues around them during birth, according to the study. 

The findings were published online today (May 15) in the journal PLOS One.

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Originally published on Live Science.

If babies had a universal trait, it would have to be their babbling. During the earliest months of their lives, babies' interactions with us basically boil down to strings of ba's, ga's and da's, punctuated by the occasional gurgle or wet raspberry.

But does this seemingly random string of sounds serve any purpose — other than to entertain besotted parents and fuel adorable social media clips? A growing body of research over the past few decades has revealed that, nonsensical though it may sound, a baby's babble actually lays the groundwork for the development of language in later life.

Amid the varied soundscape of coos, gurgles and other random noises that babies emit, babbling is recognized as a distinctive category of sound that kicks in around the 6- to 8-month mark of a baby's life. It can be defined as "the production of repetitive, speech-like syllables," said Catherine Laing, a linguistics researcher at Cardiff University in the United Kingdom, who focuses on early language development in infants. "Babble is the beginning of learning the sounds that can be used in speech," she summarized. [Why Do Babies Kick in the Womb?] 

Babble is also noticeable enough that anyone paying attention to a baby's vocalizations will notice when it begins, according to Marilyn Vihman, a professor of language and linguistic science at the University of York in the United Kingdom, who has written several books on language development: "It's a really sharp change which adults can recognize. You don't have to be a linguist to recognize it."

However, being able to detect the different phases through which babble unfolds may require a closer listen. Starting out, babies will produce a range of different consonants that they develop a habit of repeating very rhythmically. Soon after, they will typically limit their exploratory inventory to just one or two consonants that they start to repeat more frequently — as in, "babababa!" or "dadadada!" Laing told Live Science. "Having a couple of different consonants that you can produce at will seems to be a prerequisite for really beginning to do words," Vihman said. "It's kind of a predictor for being able to get word forms under control, so that you can make words that people will recognize."

At this stage, babies seem to perform these long syllabic strings as a kind of reflexive motor behavior, without recognizing its practical value. But soon, those strings graduate into shorter, more clipped expressions that start to resemble words. This is something that Vihman has explored in depth over the course of her research. It's thought that this shift is driven by the baby's growing awareness of the words that adults around them are speaking — and their desire to mimic them. "Adults are like gods in their universe, the people that provide comfort, warmth and social stimulation. So the big motivation for the baby is to be like the adults," Vihman told Live Science.

Intriguingly, research shows that deaf babies also start babbling like hearing ones; it's just slightly delayed. But that progress grinds to a halt at the stage where their babble would start to sound more word-like, because deaf babies can't hear the words of the adults they'd ordinarily be trying to mimic. In hearing babies, however, after a few more months of practicing these shorter syllables, they've "picked up on word forms that are similar to the babble they're able to produce," Vihman explained. This becomes the essential bridge that equips them to start repeating words they often hear — words that they might realize have an association with something, or an impact on their listeners. (Think: "uh-oh" and "bye-bye.") [Why Do Babies Barely Blink?]

At this point — usually between the 10- to 15-month mark — babies will dish up a melange of babble and fully formed words. By the time they have a repertoire of 20 to 30 words that they're speaking regularly, what they're doing is probably defined less as babble and more as speech, Vihman said.

And, if you have any lingering doubts about the profound influence of babble on shaping language, there are several fascinating studies that have demonstrated its importance. For example, premature babies who've had tracheostomies inserted into their lungs to help them breathe are unable to make babbling sounds like healthy babies. But research has shown that when these tracheostomies are removed, babies will start babbling — even if it's several months after it should have first begun. "They still go through a babble period before they start to produce words. They sort of pick back up," Laing said — highlighting the importance of babble in laying the groundwork for speech.

Similarly, hearing-impaired babies who receive a cochlear implant to help them hear again will soon start babbling, as if they're trying to catch up on everything they've missed. "Essentially, if you think about it, it's like rehearsing the different bits of the words that you're going to go on to produce. There's a sense of preparing yourself for word production," Laing said.

So what's the main takeaway from all of this? Since babble is a stepping-stone to language, it should be encouraged through plenty of communication with babies. And while some people might think that reciting Shakespeare is best for their offspring, you'd do just as well with a bit of baby talk. "Often parents worry, is it bad to use baby talk? There's no harm, as long as you're keeping pace with your baby's development, and that as they're understanding more, you're talking in a slightly more complex way," Vihman said.

Equally, for working parents who might feel concerned about how pressured schedules and weariness affect the quality of their time — and consequently, their chat — with their babies, Laing has an interesting perspective to share. Emerging research suggests that so long as someone is talking to them — whether another caregiver, a grandparent or a sibling — babies will benefit. "Babies can be quite resilient in terms of what they draw on as an influence," Laing said. "One-to-one interaction with parents is known to be important, but interactions with a wider range of speakers can support other kinds of learning."

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Originally published on Live Science.

In August 2018, a baby boy was born in Tokyo weighing only 9.45 ounces (268 grams) — about the weight of a bag of potato chips.

The boy had stopped growing in his mother's womb, doctors at Keio University Hospital told Reuters, and had to be delivered by an emergency Caesarean section 24 weeks into the mother's pregnancy to avoid a stillbirth. But the baby was smaller and less developed than he should have been at 24 weeks, which is the youngest age most doctors consider "viable," meaning the child can survive outside the womb. He could not breath or eat on his own, and his entire body fit inside his parents' cupped hands.

But last week, on Feb. 20, after five months of treatment, that baby boy was finally discharged from Keio University Hospital and allowed to go home with his family. Though he now weighs a healthy 7 pounds (3.2 kilograms), he leaves the hospital with the distinction of being the world's smallest surviving male baby born in recorded history. [7 Baby Myths Debunked]

"There are only four babies this small [that survived] that we know of in the history of mankind," said Dr. Edward Bell, a professor of neonatal pediatrics at the University of Iowa's Carver College of Medicine. "It's exceedingly rare. And for boys, as far as I can tell, it's unique."

Bell is the founder and webmaster of the Tiniest Babies Registry, the University of Iowa's database of the world's smallest surviving babies born since 1936. The baby boy born in Tokyo last August ranks as the fourth-smallest child on Bell's registry, and is surpassed by three baby girls from Tokyo, Illinois and Germany, all born at 25 weeks and weighing 9.34, 9.17 and 8.88 ounces (265, 260 and 252 g), respectively.

Of the registry's 210 babies (all weighing under 14 ounces, or 400 grams, at birth), Bell told Live Science that roughly 75 percent are female. This is because males develop more slowly than females, both in the womb and in adolescence.

"In these cases of extremely early [birth] or extremely small children, girls are a little more developed than boys," Bell said, and that gives baby girls a slight survival advantage. "More boys are born, but more girls survive."

Often, Bell said, babies born so small stop developing in the womb because their mother's placenta is not properly delivering the oxygen and nutrients they need to grow. The boy from Tokyo had "unusually well developed" heart, lungs, brain and kidneys for a baby of his size, Bell said (the boy's physician had to provide these details to get the baby listed on Bell's registry), but chances are he will never catch up to the average height of other kids.

"Even if his parents are of average size, he is more likely to be one of the shorter kids in his class picture, for example," Bell said.

Babies born so small also face heightened risks of developing learning disabilities and health problems than children born at full term — however, Bell said, the outcomes truly seem to differ baby-to-baby.

"Some of the babies on the registry are severely handicapped," Bell said. "Some of them are having good lives, are college graduates and very talented individuals. You see the whole spectrum."

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Originally published on Live Science.