What is a nonstress test?

A nonstress test checks the health of an unborn baby. A monitor is attached with belts to the mother’s belly and records the baby’s heart rate. Your healthcare provider will watch how the baby’s heart rate changes when the baby moves. Normally, when a healthy baby moves, the baby’s heart rate goes up.

If the test result is normal, it can reassure you and your healthcare provider that the baby is probably doing well. If the test result is abnormal, it helps you and your healthcare provider know that the baby may have problems and may need treatment.

When is it used?

Your healthcare provider may recommend this test if:

• You have a high-risk condition, such as diabetes or high blood pressure.
• The baby does not seem to be 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 are pregnant with more than 1 baby (for example, twins or triplets).
• You have too little or too much amniotic fluid.

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, which is usually 1 to 2 hours after you eat a meal

You may need to have several nonstress tests to show the baby’s well-being over time.

How do I prepare for this test?

• Pregnant women should not smoke, but if you do smoke, don’t smoke for at least 4 hours before the test. Smoking can decrease your baby’s movements.
• Your healthcare provider will tell you if you need to eat a full breakfast or lunch before the test.
• Follow any other instructions your provider gives you.

What happens during the test?

A monitor is strapped to your belly. The monitor will record the baby’s heart rate. You may be given a button to push when you feel the baby move.

The results of the test are either reactive or nonreactive.

• A reactive result means that the baby moves enough and the baby’s heart rate goes up enough to be normal. Reactive results of this test are a sign that the baby is probably doing well.
• A nonreactive result means either that the baby does not move or the heart rate does not go up enough during movements.

Often a test is nonreactive because the baby is not moving enough to get good readings. You may need to do the test again when the baby is more active.

What happens after the test?

You may need to repeat the test 3 to 7 days later. You may need to have the test several times.

As a result of this and possibly other tests, you and your provider will decide on the best options for delivering your baby.

What are the risks of this test?

This test has no risks for you or the baby.