Causes & Symptoms

Pregnancy is caused by a sperm fertilizing an egg. The first sign of pregnancy is usually a missed menstrual period, although some women bleed in the beginning. A woman's breasts swell and may become tender as the mammary glands prepare for eventual breastfeeding. Nipples begin to enlarge and the veins over the surface of the breasts become more noticeable.

Nausea and vomiting are very common symptoms that generally occur during the first three months of pregnancy. Since these symptoms are usually worse in the morning, this condition is known as morning sickness. Many women also feel extremely tired during the early weeks. Frequent urination is common, and there may be a creamy white discharge from the vagina. Some women crave certain foods, and an extreme sensitivity to smell may worsen the nausea. Weight begins to increase.

In the second trimester (13–28 weeks) a woman begins to look noticeably pregnant and the enlarged uterus is easy to feel. The nipples get bigger and darker, the skin of Caucasians may darken, and some women may feel flushed and warm. Appetite may increase. By the 22nd week, most women have felt the baby move. During the second trimester, nausea and vomiting often fade away, and the pregnant woman often feels much better and more energetic. Heart rate increases as does the volume of blood in the body.

By the third trimester (29–40 weeks), many women begin to experience a range of common symptoms. Stretch marks (striae) may develop on the abdomen, breasts and thighs, and a dark line may appear from the navel to pubic hair. A thin fluid may be expressed from the nipples. Many women feel hot, sweat easily, and often find it hard to get comfortable. Kicks from an active baby may cause sharp pains, and lower backaches are common. More rest is needed as the woman copes with the added stress of extra weight. Braxton Hicks contractions may get stronger.

At about the 36th week in a first pregnancy (later in repeat pregnancies), the baby's head drops down low into the pelvis. This shift may relieve pressure on the upper abdomen and the lungs, allowing a woman to breathe more easily. The fetus' new position, however, places more pressure on the bladder.

The average woman gains 28 lbs (12.7 kg) during pregnancy, 70% of it during the last 20 weeks. An average healthy full-term baby at birth weighs 7.5 lbs (3.4 kg), and the placenta and fluid together weigh another 3 lbs (1.3 kg). The remaining weight that a woman gains during pregnancy is mostly due to water retention and fat stores.

In addition to the typical symptoms of pregnancy, some women experience other problems that may be annoying but usually disappear after delivery. Constipation may develop as a result of food passing more slowly through the intestine. Hemorrhoids and heartburn are fairly common during late pregnancy. Gums may become more sensitive and bleed more easily; eyes may dry out, making contact lenses feel painful. Pica (a craving to eat substances other than food) may occur. Swollen ankles and varicose veins may be a problem in the second half of pregnancy, and chloasma (light brown spots) may appear on the face.

While the preceding symptoms are considered normal, there are some symptoms that may be signs of a more dangerous underlying problem. A pregnant woman experiencing any of the following should contact her doctor immediately:

      * abdominal pain
      * rupture of the amniotic sac or leaking of fluid from the vagina
      * bleeding from the vagina
      * no fetal movement for 24 hours (after the fifth month)
      * continuous headaches
      * marked sudden swelling of eyelids, hands, or face during the last three months
      * dim or blurry vision during the last three months
      * persistent vomiting