You may be asked to have a non-stress test during your pregnancy. The non-stress test may be ordered once or twice a week, but may be needed more often. This test helps to study the placenta (afterbirth) and baby’s health before delivery. The test shows how well the placenta is working to support the baby (fetus) in the uterus. If your placenta is not working well, your doctor needs to know, since it may affect your delivery.
Your doctor can tell how well the placenta is working by looking at how the baby’s heart rate responds to contractions of the uterus or the baby’s own movements. When the non-stress test is performed, you will have two belts put across your stomach. One belt will have a monitor to listen and record the baby’s heart rate. The other belt will have a monitor to pick up and record contractions.
Contractions and Your Baby’s Heart Rate
Contractions of the uterus sometimes happen during pregnancy. Usually, there are no big changes in the baby’s heart rate during a contraction. This test can study the baby’s response during contractions. If there are no contractions during the test, the test is still valid.
How Movement Affects Your Baby’s Heart Rate
Just as your heart rate gets faster when you exercise, your baby’s heart rate should also get faster when he or she moves. After the belts are put on, the baby’s heart rate is recorded for about 30 minutes to get a base line heart rate. During the test, you may be asked to change your position to help the baby move.
Your Test Results
Usually, a baby’s heart rate gets faster by 15 beats per minute during activity. This rate lasts for at least 15 seconds. If this happens at least 2 times in a period of about 30 minutes, it is called a reactive test. A reactive test result is a reassuring sign. It shows that the baby and placenta are doing well. If the test is not reactive, more tests and monitoring are sometimes needed. Your doctor may talk to you about the delivery of your baby.
Ask Your Doctor
If you have questions or concerns about your non-stress tests, call your doctor.