What is a nonstress test?A nonstress test (NST) measures the fetal heart rate in response to the fetus' movements. Generally, the heart rate of a healthy fetus increases when the fetus moves. The NST is usually performed in the last trimester of pregnancy.
How is a nonstress test performed?The actual procedure for a NST may vary, but, generally, the procedure is as follows:
- The test is often performed in a special prenatal testing area of the hospital, or in your physician's office.
- The mother lies down and has a belt placed around her abdomen with a transducer positioned over the fetal heartbeat, called an external fetal heart rate monitor.
- The fetal heart rate is recorded on the monitor and on a paper printout.
- The mother pushes a button on the monitor each time she feels fetal movement. This places a mark on the paper printout.
- Testing usually lasts for 20 to 40 minutes.
Test results of the NST:Test results of the NST may be:
- reactive (normal) - two or more fetal heart rate increases in the testing period (usually 20 minutes).
- nonreactive - there is no change in the fetal heart rate when the fetus moves. This may indicate a problem that requires further testing.
The information on this Web page is provided for educational purposes. You understand and agree that this information is not intended to be, and should not be used as, a substitute for medical treatment by a health care professional. You agree that Lucile Salter Packard Children's Hospital is not making a diagnosis of your condition or a recommendation about the course of treatment for your particular circumstances through the use of this Web page. You agree to be solely responsible for your use of this Web page and the information contained on this page. Lucile Salter Packard Children's Hospital, its officers, directors, employees, agents, and information providers shall not be liable for any damages you may suffer or cause through your use of this page even if advised of the possibility of such damages.