Results of a nonstress test are considered:

  • Reactive. Before week 32 of pregnancy, results are considered normal (reactive) if your baby's heartbeat accelerates to a certain level twice or more for at least 10 seconds each within a 20-minute window. At week 32 of pregnancy or later, if your baby's heartbeat accelerates to a certain level twice or more for at least 15 seconds each within a 20-minute window, the results are considered reactive.
  • Nonreactive. If your baby's heartbeat doesn't meet the criteria described above, the results are considered nonreactive. Keep in mind that nonreactive results might occur because your baby was asleep during the test.

If your baby's nonstress test results are nonreactive, your health care provider will likely do another prenatal test to further check your baby's health. For example:

  • Biophysical profile. A biophysical profile combines a nonstress test with ultrasound tests that evaluate your baby's breathing, movements, muscle tone and amniotic fluid level.
  • Contraction stress test. This test looks at how your baby's heart rate reacts when your uterus contracts.

Your health care provider might also ask you to have another nonstress test later in the day. Keep in mind that a reactive result is far more likely to be correct than is a nonreactive result. If you have a nonreactive nonstress test and a second nonstress test that's reactive, the second test's results are considered reliable.

Rarely, during a nonstress test, problems with a baby's heart rate are detected that require further monitoring or treatment.

Be sure to discuss the results of your nonstress test with your health care provider and what they might mean for you and your baby.

Feb. 27, 2013