A woman's body undergoes many transformations during the nine months of pregnancy. Some of these physical changes are visible, such as an expanding belly and weight gain, while others are well known, such as an enlarged uterus, morning sickness and backaches. However, a few bodily changes may be unexpected and catch some women by surprise.
"It's remarkable how a woman's body adapts to accommodate a pregnancy," said Kim Trout, a certified nurse midwife and an assistant professor of women's health at the University of Pennsylvania School of Nursing in Philadelphia.
One change that often takes some pregnant women by surprise is an increase in breast size, Trout told Live Science.
"A woman's breast size and her bra size may change several times during pregnancy," Trout said. "Some women see this as a welcome change."
A second unanticipated change is varicose veins in the genitals, Trout said. Women may expect varicose veins in their legs during pregnancy, but veins near the vagina and vulva can also become swollen and pop out usually in the third trimester, she said.
Although swollen veins in this area can be uncomfortable, they tend to go away after delivery, Trout said.
Here is a head-to-toe guide of some other physical changes that a woman's body may experience while she is pregnant.
Mouth and oral health
Bleeding gums are a common pregnancy complaint, and they may create an open portal to infections, Trout said. She explained that women are more susceptible to infections during pregnancy because the immune system tamps down.
"It's very important to keep up with oral hygiene to prevent gingivitis, or inflammation of the gums," Trout said.
But some women are afraid to go to the dentist while pregnant. Trout said it's okay to get dental X-rays during pregnancy as long as the belly is properly shielded from radiation.
Hair and nails
A woman may have many good hair days during pregnancy as estrogen increases the length of the growing phase of hair follicles often resulting in a thicker and healthier looking head of hair.
A woman may not only get more hair on her head, but also more hair growth on her body — sometimes in unwanted places, such as the upper lip, stomach, back and nipples, Trout said.
As estrogen levels fall after giving birth, women may shed more hair, Trout said. They might see clumps of hair falling out after a shower or brushing, which is a normal occurrence.
Most women find their hair returns to its normal growth and texture within four to six months after giving birth.
There also tends to be a coarsening of the texture of nails during pregnancy, making them more brittle and soft, and they may split more easily, according to The American College of Obstetricians and Gynecologists (ACOG). Nail changes may be a result of increased blood flow to the fingers and toes due to increased estrogen levels, Trout said.
Like hair, nails also tend to grow faster when a woman is pregnant, making them good targets for manicures and pedicures before giving birth.
Skin changes are very common during pregnancy, but the ones that tend to be the most bothersome to women are stretch marks, Trout said. These pinkish, purplish lines are typically seen on a woman's abdomen, breasts, backside or thighs, and they tend to itch, she said.
Stretch marks are more likely to occur in women who are obese, have rapid weight gain during pregnancy, or have large fetuses, Trout said. They may be caused by a breakdown of collagen, or connective tissue that supports the skin, in areas where the skin has had rapid growth and stretched.
Trout recommended using cocoa butter to help relieve the itchiness of stretch marks, but she also notes that there may not be a way to prevent them. They also typically shrink after giving birth and become less noticeable.
Women who are expecting may often have a "pregnancy glow." A rosy complexion may occur because of increased blood circulation to the skin. But not everything is rosy when it comes to skin changes during pregnancy. Pigment changes, such as the "mask of pregnancy," also known as melasma or chloasma, are a common occurrence.
These brownish patches of darkened skin may appear on the face around the eyes and over the cheeks and nose, due to an increase in melanin, a pigment that gives skin its color.
In addition, fluctuating hormone levels can produce a dark line in the middle of the abdomen running from the belly button to the pubic bone. Known as linea negra, this pigment change is usually more common in women with a dark complexion, and it often fades after delivery.
Pigment changes can also cause freckles and moles to darken and enlarge during pregnancy.
Acne can also worsen during pregnancy or result in breakouts in women who had clear complexions prior to pregnancy. Hormonal shifts that cause the skin to secrete more oil are likely responsible for the flare-ups.
A woman's breasts may feel more full and tender when she is pregnant, and her nipples may also be more sensitive to the touch, Trout said. For additional support, some women may sleep with a maternity bra at night, she said.
In addition, the areolas, the skin surrounding the nipples, will darken and enlarge early in pregnancy. And a woman's breasts may start leaking colostrum, a milky fluid. This typically happens during the third trimester but it can occur earlier.
As a woman's abdomen expands late in the second trimester or during the third, her belly button tends to pop out, Trout said. This could make an innie look like an outie, and an outie stick out even more, she pointed out.
Women will tend to feel warmer and sweat a lot during pregnancy due to an increased metabolic rate and increased sweat gland activity, Trout said. To stay cool, especially in the summer, she recommended that women wear loose clothing and drink plenty of water every day.
A woman is getting enough water when her urine looks yellow or clear and not the color of tea, Trout said. However, she warned that some prenatal vitamins may turn urine bright yellow.
Joints and ligaments
During a woman's first prenatal visit, her pelvis will be examined to decide if it's roomy enough to deliver a baby, Trout said.
But nature has also provided a way to help create more space in and around a woman's pelvis, and that's by secreting pregnancy hormones, including one known as relaxin, to loosen joints and ligaments (bands of connective tissue).
Relaxin not only relaxes ligaments in a woman's pelvis to prepare her for labor and delivery, but it also stretches joints and ligaments all over the body. This can lead to back pain and sciatica, or pain along the sciatic nerve — which starts in the lower back and runs through the backside and down the leg, Trout said.
She said relaxin is also responsible for the "pregnancy waddle," an altered walk resulting from a bigger belly and an increased curvature of a woman's spine. Trout said she recommends yoga to pregnant women, especially cat pose and cow pose, which are both good for lower body discomfort.
Some women say their feet grow an entire shoe size during pregnancy, and an increase in growth hormone may possibly be the reason why, Trout said. A few small studies have confirmed that feet get bigger when women are expecting and they suggest that arches in the feet flatten out.
Swelling in the feet and ankles may also occur because the body is producing extra fluids that might pool in these two locations.