what is a nonstress test

3 min read 31-12-2024

A non-stress test (NST) is a simple, painless, and non-invasive way to monitor your baby's heartbeat and your contractions during pregnancy. It's a crucial tool used to assess fetal well-being, particularly in the later stages of pregnancy. This test helps healthcare providers determine if your baby is getting enough oxygen and nutrients. Understanding what an NST is and what to expect can ease any anxieties you may have about this routine procedure.

How is a Non-Stress Test Performed?

The NST involves placing two belts around your abdomen. One belt monitors your baby's heartbeat using an ultrasound transducer. This transducer emits harmless sound waves to detect your baby's heart rate. The other belt monitors your contractions using a tocotransducer, which detects the pressure changes in your uterus.

The test usually takes about 20-30 minutes. You'll be comfortably seated or lying down during the test. It's important to remain relatively still, so your baby's heartbeat and your contractions can be accurately monitored. You might be asked to press a button on a handheld device whenever you feel a fetal movement. This helps correlate fetal movement with the heart rate.

What to Expect During the Test

During the test, a monitor displays both your baby's heart rate and your uterine contractions. The healthcare provider will be observing the tracing for patterns. A reactive NST is considered normal, where your baby's heart rate accelerates appropriately in response to movement. A non-reactive NST may indicate a need for further evaluation.

Image of a woman undergoing a non-stress test

Why is a Non-Stress Test Done?

Healthcare providers often order an NST to assess fetal well-being, particularly after 28 weeks of pregnancy. There are several reasons why your doctor might recommend this test:

High-risk pregnancy: Conditions such as preeclampsia, gestational diabetes, or multiple pregnancies can increase the risk of complications.
Reduced fetal movement: If you notice a decrease in your baby's movements, an NST can help determine if there are any issues.
Post-term pregnancy: If your pregnancy goes past your due date, an NST helps monitor your baby's health.
Previous pregnancy complications: If you experienced complications in a previous pregnancy, your doctor might recommend regular NSTs.

Understanding the Results of a Non-Stress Test

The results of an NST are categorized as either reactive (normal) or non-reactive (abnormal).

Reactive Non-Stress Test

A reactive NST is generally considered reassuring. It indicates that your baby is getting enough oxygen and nutrients. Your baby's heart rate should accelerate by at least 15 beats per minute for at least 15 seconds in response to movement.

Non-Reactive Non-Stress Test

A non-reactive NST doesn't necessarily mean there's a serious problem. However, it does indicate that further investigation is needed. Your healthcare provider may recommend additional tests, such as a biophysical profile (BPP) or contraction stress test (CST), to assess your baby's well-being more thoroughly. These additional tests provide a more comprehensive picture of your baby's health.

Frequently Asked Questions About Non-Stress Tests

Q: Is a non-stress test painful?

A: No, a non-stress test is painless and non-invasive.

Q: How long does a non-stress test take?

A: The test typically takes 20-30 minutes.

Q: What should I do if I have a non-reactive NST?

A: A non-reactive NST requires further evaluation. Your healthcare provider will likely recommend additional tests to assess your baby's well-being. Don't panic; further testing is a standard procedure.

Q: How often will I need a non-stress test?

A: The frequency of NSTs depends on your individual risk factors and your healthcare provider's recommendations.

Q: Can I eat or drink before a non-stress test?

A: Yes, you can eat and drink normally before a non-stress test.

Conclusion

A non-stress test (NST) is a valuable tool for monitoring your baby's health during pregnancy. While a non-reactive result may cause concern, it's important to remember that further testing is often necessary to determine the next steps. Your healthcare provider will explain the results and guide you through any necessary follow-up care. Remember to ask questions and voice any concerns you may have throughout the process. Understanding the process of a non-stress test can help alleviate anxiety and ensure a positive pregnancy experience.