Non-Stress Test for Fetal Well Being in Late Pregnancy

Doctor with Pregnant Woman
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Towards the end of your pregnancy, one of the key components of prenatal care is to monitor the health of your baby. While this is the purpose of prenatal care, sometimes the basics of that care may need some help. This is where late pregnancy fetal surveillance comes in handy. The non-stress test is one of the staples.

Why Do an NST

This test can be done in the later stages of pregnancy. It is more frequently used in cases where the mother is going past her assigned due date to ensure fetal well-being. In some cases, it is done as a precaution after problems in a previous pregnancy or because of high-risk factors such as diabetes, intrauterine growth retardation (IUGR), etc.

How an NST Is Done

This test is usually done in your practitioner's office. You will sit in a chair or lie on a table with fetal monitoring equipment hooked to your belly. (Though some studies show that being upright or even walking may speed the results.) The monitor will record your baby's heart rate in conjunction with any uterine activity. More frequently than not you are asked to press a button when the baby moves so that the heart rate can be seen in relation to that movement.

When Is a Test Done?

This test is most frequently done between weeks 38 and 42, however, it can be used as early as the beginning of the third trimester. It can be done as often as needed, including daily, depending on the reason it is ordered by your practitioner.

Results of the NST

Reactive and non-reactive are usually the way the results are given. Sometimes little ones don't cooperate during the testing and move. So the mother is offered a drink of something usually containing sugar or bubbles to perk the baby up. If this doesn't cause the baby to move sometimes a loud sound will be used to startle the baby into moving. Remember babies can and do sleep in utero.

Risks Involved

Generally speaking, this test is not a risky test. This is not an invasive test and does not require blood samples or invasive exams. The biggest risks include:

  • misinterpretation of the data
  • exposure to ultrasound

If you have concerns, be sure to talk to your practitioner about them before undergoing the test. They can reassure you about how they are working to minimize the risks to you and your baby.


There are two alternatives to the non-stress test: Stress testing or biophysical profile. And keeping in mind that alternatives aren't always desirable, there is also the option of delaying the non-stress test or not choosing to have the non-stress test.

What Happens After an NST

If the baby is still not as responsive as they would like you may either go to a biophysical profile, a stress test or even induction.

How and why this test is done can also vary from practitioner to practitioner. If you have questions about the test, when it's done, how often it's done, or who does it, be sure to speak up. The goal of the test is to ultimately reassure you and your practitioners that everything is going well. If you are not feeling that reassurance, be sure to speak up and ask questions.

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