Nonstress Test

What is a nonstress test?

A nonstress test uses electronic monitoring to check the health of an unborn baby. An external fetal monitor is attached to the mother and records the baby's heart rate. When a healthy baby moves, the baby's heart rate goes up.

When is it used?

You may have this test if:

You have a high-risk condition, such as high blood pressure or a baby that is not growing properly.
You had problems in a previous pregnancy, such as a baby who died at birth.
You have noticed that your baby is moving less.
You are past your due date.
You have a disease, such as diabetes.

The test is most reliable when it is done:

in the last 6 to 8 weeks of pregnancy
at the time of day when the baby is most active (1 to 2 hours after you eat a meal).

Several nonstress tests may need to be done to show the baby's well-being over time.

How do I prepare for a nonstress test?

If you smoke, do not smoke for at least 4 hours before the test.
Eat a full breakfast or lunch before the test.

What happens during the procedure?

An external electronic fetal monitor is strapped to your abdomen. You will have a button to push when you feel the baby move. The monitor will record the baby's heart rate.

The results of the test are classified as follows:

Reactive: The baby moves two or more times in 20 minutes. During at least two of these movements, the heart rate increases by 15 beats a minute and stays increased for at least 15 seconds. Reactive results of this test are a sign that the baby is healthy.
Nonreactive: Either the baby doesn't move or the heart rate doesn't rise enough during movements.

Often a test is nonreactive because the baby is not moving enough to get good readings. Then the test must be done again when the baby is more active. Sometimes drinking a glass of cranberry or orange juice will help the baby become more active. Or a device that makes a noise like a buzzer may be placed against your abdomen to awaken the baby.

If another test is again nonreactive, an ultrasound test called a biophysical profile may be done. If the well-being of the baby is still unclear, a contraction stress test may be done.

What happens after the procedure?

You may need to repeat the test 3 to 7 days later. You may need to have the test several times. In some cases your health care provider may recommend an early delivery.

What are the benefits of this test?

If the test result is abnormal, it helps identify a baby that may have problems during labor. As a result of the test, your provider may do more tests and may consider delivering the baby before labor starts.
If the test result is normal, it can reassure the mother that the baby will probably do well during labor unless new problems develop.

What are the risks of this test?

The test does not pose any risks to you or the baby.

Disclaimer: This content is reviewed periodically and is subject to change as new health information becomes available. The information provided is intended to be informative and educational and is not a replacement for professional medical evaluation, advice, diagnosis or treatment by a healthcare professional.

HIA File WOM5305F.HTM Release 9.0/2006