The nonstress test (NST) measures the fetal heart rate (FHR) as the
fetus moves. When the fetus is moving around, its heart typically
beats faster. During the NST, a belt with transducers is placed
around the pregnant woman's waist for 20-40 minutes.
is used to measure the fetus' heart rate patterns,
and a record is made on graph paper.
When the fetus is asleep or resting, it may not move for a short
period of time—sometimes as long as 40 minutes. The healthcare
provider may try to wake the fetus by having you eat or drink
something, or by using sound.
Who Should Get This Test?
Your healthcare provider may recommend this test during the late second or the third trimesters, as well as
other tests, if you have a medical condition that could put you at
risk for having problems with your pregnancy. Examples of
conditions that could put you at risk include:
The NST is not always accurate. Sometimes the test suggests a problem even when the fetus is healthy (a so-called false-positive result). If there is no change in fetal heart rate in response to fetal movement, your healthcare provider may want to try another test to confirm the NST test results.
Your healthcare provider may suggest other tests so that he or she can gather important information about the health of your fetus. A problematic test result (eg, no increase in FHR with fetal movement) often suggests that you need special care. It does not necessarily mean that your fetus is in trouble. Your healthcare provider will be able to answer questions and discuss any concerns you have about monitoring.
Please be aware that this information is provided to supplement the care
provided by your physician. It is neither intended nor implied to be a
substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER
IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the
advice of your physician or other qualified health provider prior to
starting any new treatment or with any questions you may have regarding a