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What is a non-stress test (NST) during pregnancy?

Dr. Jeanne Morrison, PhD
Family Practitioner

A non-stress test (NST) is a non-invasive method of fetal evaluation used in the last trimester of pregnancy. The NST combined accelerations in fetal heart rate with spontaneous or evoked fetal movement. It is relatively easy and inexpensive to perform and has no known contraindications. A NST examines fetal cardiac reactivity in response to fetal movement. The outcome of a NST is either reactive which is an indicator of fetal well-being or non-reactive which is an indicator of poor perinatal outcome.

A non-stress test is a prenatal screening late in pregnancy, prior to the onset of labor. It uses a fetal monitor to evaluate fetal heart-rate patterns, especially during fetal movements. Increases in the heart rate are reassuring of the baby’s well being.

It is a simple noninvasive test that involves attaching one belt to Mom’s abdomen to measure fetal heart beat and a second belt to measure contractions. It checks fetal heart rate, movement and “reactivity” of the heart rate to the movement. This is used mostly in high risk pregnancies after 28 weeks when the baby is developed enough to respond to normal stimuli. This test poses no known risks or side effects to Mother or baby.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.