Physical Changes in a Pregnant Woman
Pregnancy causes many changes in a woman's body. Most of them disappear after delivery. In some women, certain disorders, such as a skin rash or gestational diabetes (see Section 22, Chapter 258), develop during pregnancy. Some symptoms should be immediately reported to a doctor if they occur during pregnancy. They include the following:
- persistent headaches
- persistent nausea and vomiting
- dizziness
- disturbances of eyesight
- pain or cramps in the lower abdomen
- contractions
- vaginal bleeding
- leakage of amniotic fluid (described as "the water breaks")
- swelling of the hands or feet
- decreased or increased urine production
- any illness or infection
General Health: Fatigue is common, especially in the first 12 weeks and again in late pregnancy. Getting enough rest is important.
Reproductive Tract: By 12 weeks of pregnancy, the enlarging uterus may cause the woman's abdomen to protrude slightly. The uterus continues to enlarge throughout pregnancy. The enlarging uterus extends to the level of the navel by 20 weeks and to the lower edge of the rib cage by 36 weeks.
The amount of normal vaginal discharge, which is clear or whitish, commonly increases. This increase is usually normal. However, if the discharge has an unusual color or smell or is accompanied by vaginal itching and burning, a woman should see her doctor. Such symptoms may indicate a vaginal infection. Some vaginal infections, such as trichomoniasis (a protozoan infection) and candidiasis (a yeast infection), are common during pregnancy and can be easily treated (see Section 22, Chapter 247).
Breasts: The breasts tend to enlarge because hormones (mainly estrogen) are preparing the breasts for milk production. The breasts enlarge because the glands that produce milk gradually increase in number and become able to produce milk. The breasts may feel firm and tender. Wearing a bra that fits properly and provides support may help.
During the last weeks of pregnancy, the breasts may produce a thin, yellowish or milky discharge (colostrum). Colostrum is also produced during the first few days after delivery, before breast milk is produced. This fluid, which is rich in minerals and antibodies, is the breastfed baby's first food.
Heart and Blood Flow: During pregnancy, the woman's heart must work harder because as the fetus grows, the heart must pump more blood to the uterus. By the end of pregnancy, the uterus is receiving one fifth of the woman's blood supply. During pregnancy, the amount of blood pumped by the heart (cardiac output) increases by 30 to 50%. As cardiac output increases, the heart rate at rest speeds up from a normal prepregnancy rate of about 70 beats per minute to 80 or 90 beats per minute. During exercise, cardiac output and heart rate increase more when a woman is pregnant than when she is not. During labor, cardiac output increases by an additional 10%. After delivery, cardiac output decreases rapidly at first, then more slowly. It returns to the prepregnancy level about 6 weeks after delivery.
Certain heart murmurs and irregularities in heart rhythm may appear because the heart is working harder. Sometimes a pregnant woman may feel these irregularities. Such changes are normal during pregnancy. However, certain abnormal heart rhythms, which occur more often in pregnant women, may require treatment.
Blood pressure usually decreases during the 2nd trimester but may return to a normal prepregnancy level in the 3rd trimester.
The volume of blood increases by 50% during pregnancy. The amount of fluid in the blood increases more than the number of red blood cells (which carry oxygen). The result is mild anemia, which is normal. For reasons not clearly understood, the number of white blood cells (which fight infection) increases slightly during pregnancy and markedly during labor and the first few days after delivery.
The enlarging uterus interferes with the return of blood from the legs and the pelvic area to the heart. As a result, swelling (edema) is common, especially in the legs. Varicose veins commonly develop in the legs and in the area around the vaginal opening (vulva), sometimes causing discomfort. Clothing that is loose around the waist and legs is more comfortable and does not restrict blood flow. Wearing elastic support hose, resting frequently with the legs elevated, or lying on the left side usually reduces leg swelling and may ease the discomfort caused by varicose veins. Varicose veins may disappear after delivery.
Urinary Tract: Like the heart, the kidneys work harder throughout pregnancy. They filter the increasing volume of blood. The volume of blood filtered by the kidneys reaches a maximum between 16 and 24 weeks and remains at the maximum until immediately before delivery. Then, pressure from the enlarging uterus may slightly decrease the blood supply to the kidneys.
The activity of the kidneys normally increases when a person lies down and decreases when a person stands. This difference is amplified during pregnancy--one reason a pregnant woman needs to urinate frequently while trying to sleep. Late in pregnancy, lying on the side, particularly the left side, increases kidney activity more than lying on the back. Lying on the left side relieves the pressure that the enlarged uterus puts on the main vein that carries blood from the legs. As a result, blood flow improves and kidney activity increases.
The uterus presses on the bladder, reducing its size so that it fills with urine more quickly than usual. This pressure also makes a pregnant woman need to urinate more often and more urgently.
Respiratory Tract: The increased production of the hormone progesterone signals the brain to lower the level of carbon dioxide in the blood. As a result, a pregnant woman breathes faster and more deeply to exhale more carbon dioxide and keep the carbon dioxide level low. The circumference of the woman's chest enlarges slightly.
Virtually every pregnant woman becomes somewhat more out of breath when she exerts herself, especially toward the end of pregnancy. During exercise, the breathing rate increases more when a woman is pregnant than when she is not.
Because more blood is being pumped, the lining of the airways receives more blood and swells somewhat, narrowing the airways. As a result, the nose occasionally feels stuffy, and the eustachian tubes (which connect the middle ear and back of the nose) may become blocked. The tone and quality of the woman's voice may change slightly.
Digestive Tract: Nausea and vomiting, particularly in the mornings (morning sickness), are common. They may be caused by the high levels of estrogen and human chorionic gonadotropin (HCG), two hormones that help maintain the pregnancy. Nausea and vomiting may be relieved by changing the diet or patterns of eating. For example, drinking and eating small portions frequently, eating before getting hungry, and eating bland foods (such as bouillon, consommé, rice, and pasta) may help. Eating plain soda crackers and sipping a carbonated drink may relieve nausea. Keeping crackers by the bed and eating one or two before getting up may relieve morning sickness. No drugs specifically designed to treat morning sickness are currently available. If nausea and vomiting are so intense or persistent that dehydration, weight loss, or other problems develop, a woman may need to be treated with antiemetic drugs or be hospitalized temporarily and given fluids intravenously (see Section 22, Chapter 258).
Heartburn and belching are common, possibly because food remains in the stomach longer and because the ringlike muscle (sphincter) at the lower end of the esophagus tends to relax, allowing the stomach's contents to flow backward into the esophagus. Heartburn can be relieved by eating smaller meals, by not bending or lying flat for several hours after eating, and by taking antacids. However, the antacid sodium bicarbonate should not be used because it contains so much salt (sodium). Heartburn during the night can be relieved by not eating for several hours before going to bed and by raising the head of the bed or using pillows to raise the head and shoulders.
The stomach produces less acid during pregnancy. Consequently, stomach ulcers rarely develop during pregnancy, and those that already exist often start to heal.
As pregnancy progresses, pressure from the enlarging uterus on the rectum and the lower part of the intestine may cause constipation. Constipation may be worsened because the high level of progesterone during pregnancy slows the automatic waves of muscular contractions in the intestine, which normally move food along. Eating a high-fiber diet, drinking plenty of fluids, and exercising regularly can help prevent constipation.
Hemorrhoids, a common problem, may result from the pressure of the enlarging uterus or from constipation. Stool softeners, an anesthetic gel, or warm soaks can be used if hemorrhoids hurt.
Pica, a craving for strange foods or nonfoods (such as starch or clay), may develop. Occasionally, pregnant women, usually those who also have morning sickness, have excess saliva. This symptom may be distressing but is harmless.
Skin: Mask of pregnancy (melasma) is a blotchy, brownish pigment that may appear on the skin of the forehead and cheeks. The skin surrounding the nipples (areolae) may also darken. A dark line commonly appears down the middle of the abdomen. These changes may occur because the placenta produces a hormone that stimulates melanocytes, the cells that make a dark brown skin pigment (melanin).
Pink stretch marks sometimes appear on the abdomen. This change probably results from rapid growth of the uterus and an increase in levels of adrenal hormones.
Small blood vessels may form a red spiderlike pattern on the skin, usually above the waist. These formations are called spider angiomas. Thin-walled, dilated capillaries may become visible, especially in the lower legs.
 See the sidebar Skin Rashes During Pregnancy.
Hormones: Pregnancy affects virtually all hormones in the body, mostly because of the effects of hormones produced by the placenta. For example, the placenta produces a hormone that stimulates the woman's thyroid gland to become more active and produce larger amounts of thyroid hormones. When the thyroid gland becomes more active, the heart may beat faster, causing the woman to become aware of her heartbeat (have palpitations). Perspiration may increase, mood swings may occur, and the thyroid gland may enlarge. The disorder hyperthyroidism, in which the thyroid gland is truly overactive, develops in fewer than 1% of pregnancies.
Levels of estrogen and progesterone increase early in pregnancy because human chorionic gonadotropin, the main hormone the placenta produces, stimulates the ovaries to continuously produce them. After 9 to 10 weeks of pregnancy, the placenta itself produces large amounts of estrogen and progesterone. Estrogen and progesterone help maintain the pregnancy.
During pregnancy, changes in hormone levels affect how the body handles sugar. Early in pregnancy, the sugar (glucose) level in the blood may decrease slightly. But in the last half of pregnancy, the level may increase. More insulin (which controls the sugar level in the blood) is needed and is produced by the pancreas. Consequently, diabetes, if already present, may worsen during pregnancy. Diabetes can also begin during pregnancy. This disorder is called gestational diabetes (see Section 22, Chapter 258).
Joints and Muscles: The joints and ligaments (fibrous cords and cartilage that connect bones) in the woman's pelvis loosen and become more flexible. This change helps make room for the enlarging uterus and prepare the woman for delivery of the baby. As a result, the woman's posture changes somewhat.
Backache in varying degrees is common, because the spine curves more to balance the weight of the enlarging uterus. Avoiding heavy lifting, bending the knees (not the waist) to pick things up, and maintaining good posture can help. Wearing flat shoes with good support or a lightweight maternity girdle may reduce strain on the back.
 See the figure Stages of Pregnancy.
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