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What is a Nonstress Test (NST)?

A nonstress test (NST) is a routine prenatal monitoring tool that tracks your baby's heart rate over a period of time. The test is designed to observe how your baby's heart rate responds to their own movements; a healthy pattern of acceleration is a reassuring sign that your baby is receiving adequate oxygen and that their nervous system is functioning as expected.

The name refers to the fact that nothing is done to stress or stimulate the baby during the test. It is entirely non-invasive and comfortable for both mother and baby. NSTs are typically performed after 26 to 28 weeks of pregnancy and are one of the most commonly ordered tools for fetal well-being monitoring in the third trimester.

Your provider may recommend that you undergo a nonstress test if you have:

  • A pregnancy with multiple fetuses

  • An underlying medical condition, including but not limited to hypertension, heart disease, or diabetes

  • A pregnancy that has gone beyond the due date

  • Complications in current or previous pregnancies

  • A fetus with decreased movement or growth issues

  • Rhesus (Rh) sensitization – a potentially dangerous condition that is caused by the mother being Rh negative and the fetus being Rh positive

  • Low levels of amniotic fluid

Fetal heart rate monitoring may be performed once or twice a week, or more frequently, depending on your clinical picture and your provider's recommendations. They can be a routine part of high-risk pregnancy monitoring or may be ordered for specific concerns that arise during the course of an otherwise healthy pregnancy.

No special preparation is typically required for a nonstress test. You do not need to fast, and there is no anesthesia or sedation involved. Some providers suggest eating a light snack before your appointment, as a baby who has recently been fed may be more active during the test. Ask your provider if they have a specific recommendation for you.

Wear comfortable, loose clothing that allows easy access to your abdomen. Plan for the appointment to take approximately 20 to 40 minutes, though it can occasionally run longer.

When you arrive, a member of our clinical team will take your blood pressure and a brief set of vitals. You will be seated in a reclined chair, comfortable and supported, for the duration of the test. Blood pressure readings will continue at regular intervals throughout.

Two sensors are gently secured around your abdomen with elastic bands: one to track your baby's heart rate and one to detect any uterine contractions. You will be given a small button to press each time you feel your baby move. The sensors continuously record this data, allowing your provider to see how your baby's heart rate responds to their own activity.

Most nonstress tests last approximately 20 minutes. If your baby is inactive or appears to be sleeping during that window, the test may be extended by another 20 minutes. In some cases, a small buzzing device may be placed against your abdomen to stimulate activity gently; this is harmless and commonly used.

Once monitoring is complete, your provider will review the data with you. NST results are reported as either reactive or nonreactive.

  • Reactive Result: A reactive NST is reassuring. It means your baby's heart rate increased in response to movement at least twice during the test, reaching the expected acceleration threshold for your stage of pregnancy. A reactive result generally indicates your baby is receiving adequate oxygen and the nervous system is functioning as expected.

  • Nonreactive Result: A nonreactive result doesn't mean something is wrong; it just indicates that expected heart rate accelerations weren't observed, possibly because the baby was asleep or inactive. Your provider will discuss this with you and may suggest further monitoring.

An NST Test: What to Expect

An NST at Women's HealthFirst is a calm, comfortable experience. Here is a clear look at what happens from start to finish.
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Insurance Information

Most major health insurance plans cover nonstress tests ordered as part of medically indicated prenatal monitoring. Coverage may depend on your specific plan, your gestational age, and the clinical reason for the test. Out-of-pocket costs such as deductibles and coinsurance may apply. Our team can help you verify your benefits before your appointment and ensure you understand anticipated costs. We accept Aetna, Blue Shield PPO, Cigna HMO, Cofinity PPO, and most major insurance plans.

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Patient Resources

From accessing your patient portal and downloading pre-visit forms to reviewing your insurance information and exploring our patient education library, we make it easy to stay informed, prepared, and confident in your care every step of the way.

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231 E Northwest Hwy, Palatine, IL 60067

(847) 808-8884
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Frequently Asked Questions

Yes. A nonstress test is completely non-invasive and poses no risk to you or your baby. The sensors placed on your abdomen simply monitor existing fetal heart rate patterns; nothing is introduced into the body, and nothing is done to stimulate or stress the baby.

Most nonstress tests take about 20 minutes. If your baby is less active during the monitoring window, the test may be extended to 40 minutes or, if necessary, longer. In some cases, a gentle sound stimulus may be used to encourage movement.

A reactive result is reassuring. It means your baby's heart rate accelerated appropriately in response to movement at least twice during the test, a sign that your baby is receiving adequate oxygen and that the nervous system is responding normally.

A nonreactive result does not automatically mean something is wrong. It may simply mean your baby was asleep or inactive during the monitoring window. Your provider will discuss the result with you and may recommend additional monitoring, typically a biophysical profile or a contraction stress test, to gather more information.

Frequency depends on your clinical situation. Some patients are monitored once or twice a week, while others may require more frequent testing. Your provider will recommend a schedule based on your pregnancy, your health history, and any specific risk factors being monitored.

No special preparation is required. You do not need to fast. Some providers suggest eating a light snack beforehand, as a well-fed baby may be more active. Wear comfortable clothing and plan for a 20-40-minute appointment. Your provider will let you know if there are any specific instructions for your situation.

Not exactly. A nonstress test monitors fetal heart rate only. A biophysical profile (BPP) combines the NST with an ultrasound evaluation of fetal movement, breathing, muscle tone, and amniotic fluid levels. A BPP provides a more comprehensive picture and is often ordered as a follow-up if an NST result is nonreactive.