Health Library

When you pass your due date

Pregnancy complications - post-term; Pregnancy complications - overdue

Most pregnancies last 37 to 42 weeks, but some take longer. If your pregnancy lasts more than 42 weeks, it is called post-term (past due). This happens in a small number of pregnancies.

While there are some risks in a post-term pregnancy, most post-term babies are born healthy. Your health care provider can do special tests to check on the health of your baby. Keeping a close eye on the baby's health will help increase the chance of good outcomes.

I Would Like to Learn About:

Why Does it Happen?

Many women who go past 40 weeks are not really post-term. Their due date was just not calculated correctly. A due date is not exact, but an estimate.

Your due date is estimated based on the first day of your last period, the size of your uterus (womb) early in your pregnancy, and with an ultrasound early in pregnancy. However:

Many women cannot remember the exact day of their last period, which makes it hard to predict a due date.
Not all menstrual cycles are the same length.
Some women do not get an ultrasound early in pregnancy to establish their most accurate due date.

When a pregnancy truly is post-term and goes past 42 weeks, no one knows for sure what causes it to happen.

What are the Risks?

If you have not given birth by 42 weeks, there are greater health risks for you and your baby.

The placenta is the link between you and your baby. As you pass your due date, the placenta may not work as well as before. This could lessen the amount of oxygen and nutrients that the baby gets from you. As a result, the baby:

May not grow as well as before.
May show signs of fetal stress. This means the baby's heart rate does not react normally.
May have a harder time during labor.
Has a higher chance of stillbirth (being born dead). Stillbirth is not common but begins to increase the most after 42 weeks gestation.

What if my Pregnancy Goes Past the Due Date?

Until you reach 41 weeks, your provider may not do anything unless there are problems.

If you reach 41 weeks (1 week overdue), your provider will do tests to check on the baby. These tests include a non-stress test and biophysical profile (ultrasound).

The tests may show that the baby is active and healthy, and the amount of amniotic fluid is normal. If so, your provider may decide to wait until you go into labor on your own.
These tests can also show that the baby is having problems. You and your provider must decide if labor needs to be induced.

When you reach between 41 and 42 weeks, the health risks to you and your baby become even greater. Your provider will likely want to induce labor. In older women, especially older than 40, it may be recommended to induce labor as early as 39 weeks.

How Will the Doctor Induce Labor?

When you have not gone into labor on your own, your provider will help you start. This may be done by:

Using a medicine called oxytocin. This medicine can cause contractions to start and is given through an IV line.
Placing medicine suppositories inside the vagina. This will help ripen (soften) the cervix and may help labor to start.
Breaking your water (rupturing the membranes which hold amniotic fluid) can be done for some women to help labor start.
Putting a catheter or tube in the cervix to help it begin to dilate slowly.
Some combination of these methods may also be used by your provider.

Will I Need a C-section?

You will only need a C-section if:

Your labor cannot be started by your provider with the techniques described above.
Your baby's heart rate tests show possible fetal distress.
Your labor stops progressing normally once it has started.

References

Levine LD, Srinivas SK. Induction of labor. In: Landon MB, Galan HL, Jauniaux ERM, et al, eds. Gabbe's Obstetrics: Normal and Problem Pregnancies. 8th ed. Philadelphia, PA: Elsevier; 2021:chap 12.

Thorp JM, Grantz KL. Clinical aspects of normal and abnormal labor. In: Resnick R, Copel JA, Dugoff L, et al, eds. Creasy and Resnik's Maternal-Fetal Medicine: Principles and Practice. 9th ed. Philadelphia, PA: Elsevier; 2023:chap 40.

Review Date: 5/14/2024

Reviewed By: John D. Jacobson, MD, Professor Emeritus, Department of Obstetrics and Gynecology, Loma Linda University School of Medicine, Loma Linda, CA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

A.D.A.M., Inc. is accredited by URAC, for Health Content Provider (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics. This site complies with the HONcode standard for trustworthy health information: verify here.

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. No warranty of any kind, either expressed or implied, is made as to the accuracy, reliability, timeliness, or correctness of any translations made by a third-party service of the information provided herein into any other language. © 1997- 2024 A.D.A.M., a business unit of Ebix, Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

A.D.A.M. content is best viewed in IE9 or above, Firefox and Google Chrome browser.