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Post-term Pregnancy

(Postdate Pregnancy; Postdates; and Prolonged Pregnancy)

by Cynthia M. Johnson, MA

Home | Health Information Center | Disease, Condition, & Injury Fact Sheets | Article

Definition

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.

Causes

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

Symptoms

There are no symptoms.

Diagnosis

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

Treatment

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

Prevention

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

RESOURCES:

The American College of Obstetricians and Gynecologists
https://www.acog.org

Office on Women's Health
https://www.womenshealth.gov

CANADIAN RESOURCES:

The Society of Obstetricians and Gynaecologists of Canada
https://sogc.org

Women's Health Matters—Women's College Hospital
http://www.womenshealthmatters.ca

References:

Labor induction. EBSCO DynaMed website. Available at: https://www.dynamed.com/management/labor-induction. Accessed September 15, 2021.

Labor induction. Family Doctor—American Academy of Family Physicians website. Available at: https://familydoctor.org/labor-induction. Accessed September 15, 2021.

Postterm pregnancy. EBSCO DynaMed website. Available at: https://www.dynamed.com/condition/postterm-pregnancy. 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: https://familydoctor.org/pregnancy-expect-youre-past-due-date. 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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