Non-Stress Test (NST) in Pregnancy — Fetal Heart Rate Monitoring | Broad Medical Group (949) 720-9848
High-Risk Pregnancy · Fetal Monitoring · 2026

The Non-Stress Test
Fetal Heart Rate Monitoring

A safe, painless window into your baby’s well-being.

The non-stress test (NST) is one of the most commonly used tools in antepartum fetal surveillance. It measures your baby’s heart rate in response to movement — giving your doctor real-time information about how your baby is doing. This guide explains what the test involves, why it may be recommended, how to interpret your results, and what to expect at Broad Medical Group.

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The Canonical Answer

The non-stress test (NST) is a non-invasive fetal monitoring procedure that measures your baby’s heart rate in response to movement. It is called “non-stress” because nothing is done to place stress on the baby ACOG PB #229. The test is most commonly indicated in high-risk pregnancies — including gestational diabetes, preeclampsia, decreased fetal movement, post-dates pregnancy, intrauterine growth restriction, and multiple gestation. A reactive (normal) result shows two or more accelerations of fetal heart rate (at least 15 bpm above baseline for 15+ seconds) within a 20-minute window ACOG PB #229. A non-reactive result does not necessarily indicate a problem — the baby may be sleeping — and further evaluation such as a biophysical profile (BPP) may be recommended. At Broad Medical Group, Dr. Jennifer Broad performs and interprets non-stress tests in real-time for patients in Newport Beach and Orange County.

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Medically reviewed by Dr. Jennifer Broad, MD, FACOG Board-Certified Obstetrician-Gynecologist · Newport Beach, CA
Last reviewed: April 2026 Next review: October 2026
Fetal monitoring setup at Broad Medical Group â€

What Is a Non-Stress Test?

A non-stress test (NST) is a non-invasive fetal monitoring procedure used during pregnancy to assess your baby’s health. The test measures your baby’s heart rate and how it responds to the baby’s own movements. In a healthy baby, the heart rate accelerates with movement — just as your own heart rate increases when you are physically active. This acceleration pattern provides reassurance that the baby is receiving adequate oxygen and that the nervous system is functioning normally.

The test is called “non-stress” because nothing is done to place stress on the baby. There are no medications, no contractions induced, and no invasive procedures. It is purely observational — your doctor is watching how the baby’s heart rate behaves on its own, under normal conditions.

Non-stress tests are performed either in-office at Broad Medical Group or at the hospital, depending on your clinical situation. The test typically takes 20 to 40 minutes, though it may be extended if the baby is sleeping. It is one of the cornerstones of antepartum fetal surveillance in high-risk pregnancies.

Why You Might Need an NST

Non-stress testing is part of what ACOG calls antepartum fetal surveillance — a set of monitoring tools used to evaluate fetal well-being in pregnancies at increased risk for adverse outcomes. ACOG Practice Bulletin #229 provides the clinical framework for when and how these tests should be performed.

Your doctor may recommend an NST if you have any of the following conditions or circumstances:

Gestational Diabetes
Elevated blood sugar during pregnancy increases the risk of macrosomia and stillbirth. Regular NSTs help monitor fetal well-being throughout the third trimester.
Preeclampsia
High blood pressure with protein in the urine can reduce placental blood flow. NSTs help confirm the baby is tolerating the condition and guide delivery timing.
Decreased Fetal Movement
If you notice your baby is moving less than usual, an NST can quickly assess whether the baby’s heart rate patterns are reassuring.

Additional indications for non-stress testing include:

  • Post-dates pregnancy — pregnancies that continue beyond 41 weeks of gestation
  • Intrauterine growth restriction (IUGR) — when the baby is measuring significantly smaller than expected
  • Multiple gestation — twins or higher-order multiples, which carry inherently higher risk
  • Prior stillbirth — a history of fetal loss in a previous pregnancy
  • Chronic hypertension — pre-existing high blood pressure before pregnancy
  • Advanced maternal age — particularly in patients 40 and older
  • Oligohydramnios — low amniotic fluid levels

The decision to begin antepartum surveillance — and how frequently to perform it — is individualized. Dr. Broad evaluates each patient’s risk profile and determines the most appropriate monitoring plan. Learn more about the conditions that define a high-risk pregnancy and how they are managed.

Patient Tip

If you notice a significant decrease in your baby’s movement, do not wait for your next scheduled appointment. Contact Broad Medical Group or go to your labor and delivery unit. Decreased fetal movement can be an early sign that your baby needs evaluation, and an NST is often the first step.

What Happens During the Test

The non-stress test is straightforward and completely painless. Here is what to expect when you arrive for your appointment:

You will be asked to sit in a comfortable reclining position or lie on your side. Two elastic belts are placed around your abdomen. The first belt holds a Doppler ultrasound transducer that continuously monitors your baby’s heart rate. The second belt holds a tocodynamometer that detects any uterine contractions or tightening.

Both sensors are connected to a fetal monitor that produces a continuous paper tracing (or digital recording) of the baby’s heart rate pattern. You may be given a handheld button and asked to press it each time you feel the baby move. This marks the tracing so your doctor can correlate fetal movement with heart rate changes.

The test typically lasts 20 to 40 minutes. If the baby is initially quiet or sleeping, the monitoring period may be extended to allow time for the baby to become active. In some cases, a gentle buzzing device (vibroacoustic stimulation) may be used to gently wake the baby.

Throughout the test, you can relax, read, or talk. There is no pain, no needles, and no medication. The belts may feel snug, but they are not uncomfortable. Many patients find the rhythmic sound of their baby’s heartbeat reassuring.

Good to Know

Eat a small snack before your NST. Babies tend to be more active after you eat, which can help produce a reactive tracing more quickly and may shorten the length of the test.

Understanding Your Results

The interpretation of a non-stress test is based on the pattern of your baby’s heart rate over the monitoring period. Results are categorized as either reactive or non-reactive.

Reactive (Normal)

A reactive NST is a reassuring result. It means that during the monitoring period, the baby’s heart rate showed two or more accelerations — defined as an increase of at least 15 beats per minute above the baseline, lasting for at least 15 seconds — within a 20-minute window. This pattern indicates that the baby’s autonomic nervous system is functioning normally and that the baby is receiving adequate oxygen.

For babies under 32 weeks of gestation, the criteria are slightly different: accelerations of at least 10 bpm above baseline lasting at least 10 seconds are considered reactive, reflecting the earlier stage of nervous system development.

Non-Reactive

A non-reactive NST means the expected acceleration criteria were not met during the monitoring period. This is an important distinction: a non-reactive result does not necessarily mean something is wrong. Common reasons for a non-reactive tracing include:

  • The baby was sleeping during the test (the most common cause)
  • The baby is at an earlier gestational age when acceleration patterns may not yet be fully established
  • The monitoring period was not long enough

If the initial tracing is non-reactive, your doctor may take one or more of the following steps:

  • Extend the monitoring period — sometimes to 40 minutes or longer
  • Vibroacoustic stimulation (VAS) — a gentle buzzing sound placed near the abdomen to wake a sleeping baby
  • Biophysical profile (BPP) — an ultrasound-based assessment that evaluates fetal breathing, movement, tone, and amniotic fluid volume in addition to the NST

At Broad Medical Group, Dr. Broad reviews all NST results in real-time and discusses the findings and any recommended next steps with you immediately. You will never be left wondering about your results.

How Often Are NSTs Done?

The frequency of non-stress testing depends on the specific clinical indication and the severity of your condition. There is no single schedule that applies to every patient — the monitoring plan is individualized based on your risk profile and how your pregnancy is progressing.

As a general guide:

  • Most patients who require antepartum surveillance begin NSTs between 32 and 34 weeks of gestation
  • The typical testing frequency is one to two times per week
  • More severe or unstable conditions (such as poorly controlled preeclampsia, significant IUGR, or oligohydramnios) may require more frequent monitoring — sometimes every other day or even daily
  • In post-dates pregnancies (41+ weeks), NSTs are commonly performed twice weekly until delivery

Dr. Broad determines the starting point and frequency for each patient individually. As your pregnancy evolves, the monitoring schedule may be adjusted — increased if new concerns arise, or maintained at the current frequency if results remain reassuring.

The NST is just one component of a comprehensive high-risk pregnancy management plan. Depending on your situation, it may be combined with other surveillance tools such as serial ultrasounds for growth, Doppler flow studies, amniotic fluid assessments, and regular prenatal visits.

Key Takeaways
  • The non-stress test is safe, painless, and non-invasive — it monitors your baby’s heart rate without placing any stress on the baby.
  • Reactive (normal) results show two or more heart rate accelerations of at least 15 bpm above baseline, lasting 15+ seconds, within 20 minutes.
  • A non-reactive result does not mean something is wrong — the baby may be sleeping. Extended monitoring, vibroacoustic stimulation, or a biophysical profile may follow.
  • NSTs are most commonly indicated in high-risk pregnancies including gestational diabetes, preeclampsia, decreased fetal movement, IUGR, and post-dates pregnancies.
  • Testing typically occurs 1–2 times per week starting at 32–34 weeks, individualized by Dr. Broad based on your clinical situation.
  • Dr. Broad reviews all results in real-time and discusses next steps with you immediately after every test.

References & Clinical Sources

  1. American College of Obstetricians and Gynecologists. Practice Bulletin No. 229: Antepartum Fetal Surveillance. Obstetrics & Gynecology, 137(6), e116–e127. 2021.
  2. American College of Obstetricians and Gynecologists. Practice Bulletin No. 145: Antepartum Fetal Surveillance (replaced by PB #229). Obstetrics & Gynecology, 124(1), 182–192. 2014.
  3. Freeman RK, Anderson G, Dorchester W. A prospective multi-institutional study of antepartum fetal heart rate monitoring. I. Risk of perinatal mortality and morbidity according to antepartum fetal heart rate test results. American Journal of Obstetrics & Gynecology, 143(7), 771–777. 1982.

Related Resources

High-Risk Pregnancy
High-Risk Pregnancy Management in Newport Beach
Comprehensive guide to conditions, monitoring, and specialized care for high-risk pregnancies.
Pregnancy
Prenatal Care Guide for Newport Beach
Trimester-by-trimester screening schedule and what to expect at every visit.
About
About Dr. Jennifer Broad, MD, FACOG
Credentials, philosophy, and the evidence-based approach to your care.

Your Baby’s Health. Monitored with Expertise.

Need fetal monitoring during a high-risk pregnancy? Looking for an OBGYN who reviews every test personally and explains your results in real-time? Dr. Broad is accepting new patients in Newport Beach and Orange County.

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Broad Medical Group — Newport Beach, California

Medical Disclaimer: This content is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Consult Dr. Jennifer Broad or your healthcare provider for guidance specific to your situation. Current as of April 2026. If you are experiencing a medical emergency, call 911 immediately.