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Postterm Pregnancy and Postmaturity


Julie S. Moldenhauer

, MD, Children's Hospital of Philadelphia

Last full review/revision Jul 2021| Content last modified Jul 2021
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A postterm pregnancy is one that lasts 42 weeks or more. In postmaturity, the placenta can no longer maintain a healthy environment for the fetus because the pregnancy has lasted too long.

On average, pregnancy lasts 280 days (40 weeks) from the first day of the last menstrual period. In most pregnancies that go a little beyond, up to 41 to 42 weeks, no problems develop. However, beyond that time, problems may develop because the placenta often cannot continue to deliver adequate nutrients to the fetus. This condition is called postmaturity Postterm Newborn A postterm newborn is a baby delivered after 42 weeks of gestation. Near the end of a term pregnancy, the function of the placenta decreases, providing fewer nutrients and less oxygen to the... read more .

Postterm pregnancies increase the risk of problems such as

A postmature fetus may have dry, peeling skin, overgrown nails, a large amount of scalp hair, deep creases on the palms and soles, little body fat, and skin that is stained green or yellow by meconium.

Did You Know...

  • If a pregnancy lasts more than 42 weeks, the placenta may malfunction, causing problems for the fetus.

To diagnose a postterm pregnancy, doctors must accurately determine the due date Due date Pregnancy begins when an egg is fertilized by a sperm. For about 9 months, a pregnant woman’s body provides a protective, nourishing environment in which the fertilized egg can develop into... read more . If women have regular menstrual cycles, doctors can calculate the due date based on when their last menstrual period was. But the most accurate way to date a pregnancy is ultrasonography, especially if done during the first 12 weeks of pregnancy.

Labor is started (induced Induction of Labor Induction of labor is the artificial starting of labor. Usually, labor is induced by giving the woman oxytocin, a drug that makes the uterus contract more frequently and more forcefully. The... read more ) if the fetus is having problems or amniotic fluid has decreased too much. Even if there are no obvious problems, doctors consider inducing labor at 41 weeks. Typically after 42 weeks, labor is induced.

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Abortion is defined as the intentional ending of a pregnancy by surgery or drugs. Which of the following statements about abortion in the United States is most accurate? 
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