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Nonstress Test
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Lab Tests

Nonstress Test

A nonstress test is a safe, painless procedure used during pregnancy to monitor your baby's heart rate in response to their own movements or uterine contractions.

Overview

The nonstress test (NST) measures the fetal heart rate. In healthy babies, the heart rate typically increases during movement. If the heart rate does not increase, it may indicate the baby is not receiving enough oxygen, which may necessitate further testing, treatment, or the induction of labor.

What is it used for?

The test checks the baby's health before birth, typically during the third trimester (after 28 weeks).

Why do I need a nonstress test?

Your provider may order this test if:

  • The baby is moving less than usual.
  • The pregnancy is overdue (42 weeks or beyond).
  • You have a high-risk chronic condition like high blood pressure, diabetes, heart disease, or a clotting disorder.
  • You had complications in a previous pregnancy.
  • There is Rh incompatibility.
  • You are carrying multiples (twins, triplets, etc.).

What happens during a nonstress test?

The procedure generally follows these steps:

  • You will lie on a reclining chair or exam table.
  • Gel is applied to your abdomen, and two belts are attached: one to measure the baby's heartbeat and one to record contractions.
  • The monitor records the heart rate and contractions.
  • You may be asked to press a button when you feel the baby move.
  • The test usually lasts 20 to 30 minutes.
  • If the baby is inactive, the provider may use a buzzer or suggest a snack to help wake the baby.

Will I need to do anything to prepare?

No special preparation is required, though your provider may ask you to empty your bladder before the test.

Are there any risks?

There are no risks to you or your baby from a nonstress test.

What do the results mean?

  • Reactive or Reassuring: The baby's heart rate increased two or more times during the test.
  • Nonreactive: The heart rate did not increase or the baby was not moving.

A nonreactive result does not necessarily mean there is a problem, as the baby may simply have been asleep. However, your provider will likely perform follow-up tests to ensure the baby's safety.

Is there anything else I need to know?

Additional noninvasive tests include the biophysical profile (which combines an NST with an ultrasound) and the contraction stress test (which monitors how the baby's heart reacts to uterine contractions).

Frequently Asked Questions

The test typically lasts 20 to 40 minutes. If the baby is sleeping and does not move, the test may be extended to 40 minutes. To help wake the baby, you can try drinking a cold sweet beverage, eating a snack, or gently moving around, though you must remain still while the monitor is attached.
Yes, you can eat and drink during the test. In fact, consuming a small snack or a cold, sweet drink is often recommended if the baby is not moving, as this can stimulate fetal activity and help achieve a reactive result.
reactive test means the baby's heart rate increased appropriately during movement, which is a normal and reassuring sign that the baby is healthy. A non-reactive test means the heart rate did not show the expected acceleration, which may indicate the baby was sleeping or could be a sign of reduced oxygen; it is not a diagnosis of a problem but often requires a repeat test or further monitoring.
Yes, the nonstress test is completely safe for both you and your baby. It uses external ultrasound sensors to monitor heart rate and contractions and does not involve radiation, needles, or any invasive procedures.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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