The nonstress test (NST) measures the fetal heart rate 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. Doppler
ultrasound 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.
Your healthcare provider may recommend this test, 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. 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 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.
Last reviewed July 2007 by Ganson Purcell Jr., MD, FACOG, FACPE
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 medical condition.
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