Post-term Pregnancy

(Postdate Pregnancy; Postdates; and Prolonged Pregnancy)


A normal pregnancy lasts 38 to 42 weeks. A post-term pregnancy lasts longer than 42 weeks. This raises the risk of certain health problems. Proper prenatal care can improve outcomes.


The most common cause is an incorrect due date. In other people, the exact cause is not known. Changes in hormone levels or certain defects with the baby may play a role.

Risk Factors

Things that may raise the risk are:

  • Prior post-term pregnancy
  • First pregnancy
  • Older age of the mother
  • Obesity
  • Having a boy


There are no symptoms.


The doctor will review your history to make sure the due date is right. You may need:

  • A pelvic exam to check the cervix for signs that labor may be near
  • An ultrasound to see how much fluid is around the baby, what position the baby is in, or to check on your baby's movements
  • Fetal monitoring to check baby's heartbeat


The goal of treatment is for labor to begin. Options are:

Close Monitoring

Some women and their healthcare providers choose to wait for labor to begin on its own. During this time, the doctor will watch the baby’s heart rate, fluid levels around the baby, and the baby's breathing and movements.

The doctor may start labor if there are any problems or the pregnancy lasts longer than 42 weeks.

Starting Labor

If labor has not started on its own, there are ways the doctor can start it. These include:

  • Medicines to help soften and open the cervix.
  • Breaking the water by making a small tear in the sac around the baby
  • Separating the membranes around the baby by running a finger around the neck of the cervix
  • Giving a medicine called oxytocin to start contractions

Starting labor rather than waiting lessens the chance of needing a cesarean section.

Full Term Fetus with Intact Membranes

Copyright © Nucleus Medical Media, Inc.


There is no way to prevent a post-term pregnancy.


The American College of Obstetricians and Gynecologists
Office on Women's Health


The Society of Obstetricians and Gynaecologists of Canada
Women's Health Matters—Women's College Hospital


Labor induction. EBSCO DynaMed website. Available at: Accessed September 15, 2021.
Labor induction. Family Doctor—American Academy of Family Physicians website. Available at: Accessed September 15, 2021.
Postterm pregnancy. EBSCO DynaMed website. Available at: Accessed September 15, 2021.
Pregnancy: What to expect when you're past your due date. Family Doctor—American Academy of Family Physicians website. Available at: Accessed September 15, 2021.
Last reviewed July 2021 by EBSCO Medical Review Board Mary-Beth Seymour, RN
Last Updated: 9/15/2021

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