Nonstress Test (NST)

Who Gets the Test?

The nonstress test is a common test for pregnant women. You may need it if you're overdue or have complications during pregnancy. Your doctor may suggest it if your baby seems to be moving less than usual.

What the Test Does

The nonstress test is a simple, noninvasive way of checking on your baby's health.

The test records your baby's movement, heartbeat, and contractions. It notes changes in heart rhythm when your baby goes from resting to moving, or during contractions if you're in labor. Your baby's heart should beat faster when active -- just like yours. The NST can reassure you that your baby is healthy and getting enough oxygen.

It's called a nonstress test because the test won’t bother your baby. Your doctor won't use medications to make your baby move. The NST records what your baby is doing naturally.

How the Test Is Done

The NST is safe for you and the baby. You'll lie down with two belts around your belly. One measures your baby's heartbeat and the other measures contractions. When you feel the baby kick or move, you may press a button so your doctor can see how the baby's heartbeat changed while moving. The test will take about 20 minutes.

If your baby seems to be sleeping, a nurse may try to wake up your baby by ringing a bell, moving your belly or by using an acoustic stimulator.

What to Know About Test Results

A normal nonstress test shows that your baby is getting enough oxygen and is doing well. If the results are unusual, your doctor may suggest further testing.

If your baby doesn't move during the nonstress test, try not to worry. Many women with abnormal results turn out to have perfectly healthy babies. Sometimes, babies sleep through the whole thing. The test is not checking "movement," but evaluating reactivity of the heartbeat. There may or may not be appreciable movement during the test.

How Often the Test Is Done During Your Pregnancy

Women might start getting weekly or twice weekly get a nonstress testing after 28 weeks if you have a high risk pregnancy. (Before 28 weeks, the test isn't accurate.) Some may only need one isolated NST if the baby is not moving well. You may need the test more often depending on your situation. Ask your doctor.

Other Names for This Test

Cardiotocography

Tests Similar to This One

Contraction stress test

WebMD Medical Reference Reviewed by Kecia Gaither, MD, MPH on June 01, 2016

Sources

SOURCES:

Pagana, K.D. Mosby’s Diagnostic and Laboratory Test Reference, 10th ed. Mosby: 2010.

ACOG: Special Tests for Monitoring Fetal Health.

Johns Hopkins Manual of Gynecology and Obstetrics, 4th Edition. Lippincott Williams & Williams, 2010.

© 2016 WebMD, LLC. All rights reserved.

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