Pregnancy

In the time it takes to count to 10, more than 60 women become pregnant around the world. Pregnancy is normally a 40-week journey, usually measured from the date of a woman's last menstrual period to the birth of her baby. It's a time of rapid development for the soon-to-be-baby, and sometime bewildering changes for the mother.

Pregnancy is divided into three periods, known as trimesters. Each lasts about 13 weeks. The trimesters are roughly equivalent to specific developmental stages.

First trimester: A baby's body and organ systems begin their initial development. This is the period during which most miscarriages and birth defects occur. It is also when women tend to experience morning sickness, fatigue, and other pregnancy-related symptoms. By the end of the first trimester, the average fetus is 3 inches long and weighs about an ounce.

Second trimester: During the second trimester, a baby grows skin and hair, and even develops fingerprints. A heartbeat can be heard with a stethoscope. For moms, morning sickness tends to fade, and sleep improves. But other problems, such as back pain, leg cramps, and heartburn, may appear. The baby's first movements are usually felt during the second trimester. By its end, the average baby is about 14 inches long and weighs more than 2 pounds. Babies delivered at the end of the second trimester may be able to survive with the help of medical technology.

Third trimester: The final stretch for baby and mother. It's a time of rapid growth and maturation for the baby. Toward the end of the third trimester, the baby usually moves into the "head down" position in preparation for birth. At 38 weeks, the baby is considered full term and can make its appearance at any time. Because the baby is getting so big, a mom can experience shortness of breath, hemorrhoids, and trouble sleeping. Toward the end of the third trimester, the average baby is 19 to 21 inches long and weighs between 6 and 10 pounds.

Pregnancy Articles

Study finds weak link between birth control and breast cancer

A new study shows that hormonal birth control could raise a woman’s risk of breast cancer, but only by a small amount. However, women over age 40 who use hormonal birth control may want to ask their doctors about whether they should shift to nonhormonal contraception. (Locked) More »

Miscarriage

A miscarriage is the sudden loss of a pregnancy within the first 20 weeks of gestation. Up to 1 in 5 women who know they are pregnant will miscarry. Most miscarriages that occur in the first 12 weeks of pregnancy are caused by genetic problems. Most early miscarriages can't be prevented or stopped. Later miscarriages may be due to problems with a woman's reproductive system, such as the cervix, uterus, placenta, or because of other complications of pregnancy. Infection and blood-clotting problems can also cause miscarriage. More »

Study elucidates health risks for DES daughters

The synthetic estrogen diethylstilbestrol (DES) was widely prescribed in the 1940s, '50s, and '60s to prevent miscarriage and premature delivery. Its dangers were first revealed in the early 1970s, when Harvard-affiliated researchers linked the drug to a rare cancer of the vagina and cervix in the daughters of women who took DES while pregnant. In 1971, the FDA issued a warning against its use by pregnant women, but five to 10 million pregnant women and their babies had already been exposed. In the following decades, many other health problems were discovered among DES daughters and have been documented in a follow-up study. (Locked) More »

Understanding Infertility

  Surprising news for both men and women: your biological clocks have been ticking for longer than you think. The results of recent research show fertility begins to decline in women as early as age 27 and in men around age 35. But the news isn't all bad; the fertile period (or open window for conception) during a woman's cycle remains the same length between ages 19 and 39. The study, published in the May 2002 issue of the journal Human Reproduction, involved 782 European couples practicing the rhythm method of contraception. Women recorded their daily body temperatures, the days they had sex, and the days of their menstrual bleeding. Fertility was measured by the probability of becoming pregnant per menstrual cycle. More »