How a Pregnancy Stress Test Works

Female doctor touching pregnant patient's belly

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The pregnancy stress test, as it's called by many mothers, is a test that goes by many other names, including the oxytocin challenge test (OCT). It was later renamed as the contraction stress test (CST). This is one of the many potential tests that can be done to check on the health and well-being of your baby in pregnancy.

Why the Test Is Done

The contraction stress test is done to see how well your baby will respond to the stress of contractions during labor. This can be done for a variety of reasons in late pregnancy, or even in early labor.

How the Test Is Done

You will be taken to the hospital where you can have IV fluids and fetal monitoring, should intervention become necessary. Usually, a small amount of Pitocin will be given to you via the IV, and you will be monitored to see how your baby responds to the contractions via the electronic fetal monitor. They are looking at how your baby's heart rate responds on the fetal monitor.

When the Test Is Done

This test is usually done at the very end of pregnancy, prior to an induction of labor.

How the Results Are Given

The results of the contraction stress test are given as pass or fail.

Risks Involved

There are risks involved, which is why this is done in the hospital. It is a safety precaution. This test may actually jump-start labor. This is why it is done at the end of pregnancy, to avoid preterm labor. The use of Pitocin may cause fetal distress. This is why it is done in the hospital where your baby can be monitored and intervention can be used. This could be anything from oxygen for mom, to medications to stop contractions, or even a cesarean done immediately in extreme circumstances.


There are alternatives to this test. Which one may be used will depend on what is going on with your pregnancy, how far along you are and other factors. The alternatives include the non-stress test (NST) or the biophysical profile (BPP). These are tests that can usually be done in the office of your midwife or physician.

Where to Go From Here

If the baby passes the pregnancy stress test, you may either be asked to do other testing or you may be allowed to wait until natural labor starts. This may be repeated later if needed. You may also have your labor induced, or cesarean birth may be decided upon if your baby does not appear to deal well with contractions.

You will typically have time to talk to your doctor or midwife about the outcome of the test and the next steps before any decision is made. This is also one of those appointments where having your support people with you would be helpful. Talk to your doctor or midwife and ask them when this test might be needed and what alternatives you may have as options. Good communication is the key for you and your baby's health.

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Article Sources
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  1. U.S. Department of Medicine, MedlinePlus. Monitoring your baby before labor. Updated April 19, 2018.

  2. U.S. Department of Veterans Affairs, Veterans Health Library. Nonstress and contraction stress tests. Updated December 10, 2018.

  3. Różańska-Walędziak A, Czajkowski K, Walędziak M, Teliga-Czajkowska J. The present utility of the oxytocin challenge test-a single-center study. J Clin Med. 2020;9(1). doi:10.3390/jcm9010131

Additional Reading
  • Gabbe, S, Niebyl, J, Simpson, JL. Obstetrics: Normal and Problem Pregnancies, 6th Edition.

  • Simkin, P and Ancheta, R. Wiley-Blackwell. The Labor Progress Handbook, 2nd Edition.