McKesson Clinical Reference Systems: Women's Health Advisor 2002.2

What is a nonstress test?

A nonstress test is a procedure that uses external 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 heart rate goes up.

When is it used?

You may have this test if:

• You have a high-risk condition.
• You had complications in a previous pregnancy, such as a stillbirth.
• 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.

What happens during the procedure?

An external electronic fetal monitor is strapped to your abdomen. You will have a button to push when the baby moves. The monitor records the baby's heart rate on a graph. It makes a mark on the paper when you push the button.

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.

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.

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