What Is NST in Pregnancy? Everything You Should Know

A nonstress test (NST) is performed during a pregnancy screening. It is related to the fetus, meaning to check for fetal heart rate. NST is also known as the fetal nonstress test. Here, the doctor notices the response of the fetus to contractions or movements. The test is painless and safe for the mother as well as the unborn, just like its name ‘nonstress’.

The intention of NST is to diagnose if the fetus is getting sufficient oxygen and if it is healthy. Just like when we move physically our heart rate changes or increases, for the fetus too the heart rate alters as it kicks or moves. The healthcare professional notices these changes or reactions to movement for the fetus.

If the fetus does not respond to the movement, it can indicate no movement or something is amiss. Sometimes NST is performed to understand if additional tests are required to verify the fetus's condition or if inducing labor is a requirement. Let us learn about what is NST in pregnancy, the test results, and more.

Reasons of Getting a Nonstress Test in a Pregnancy

A nonstress test is usually recommended after 28 weeks into pregnancy because the fetal heart rate begins responding to movements thereafter. Some reasons why NST is done in a pregnancy are:

· In a high-risk pregnancy where issues such as high blood pressure or diabetes exist. NST helps monitor the fetus during conception.

· If the fetus is Rh positive and if you are Rh negative, antibodies that your body produces could harm the baby. An NST can keep a track of the fetus’s wellness in this case.

· If you are having triplets, twins, or more, then the pregnancy is susceptible to complications, where NST can be used as a safe way to keep a check on fetuses heart rate.

· NST is often recommended if you feel the amount of movement by the fetus has reduced or there is no or not much movement at all.

· If the fetus does not show expected growth as per the gestational age, then NST is a way to test for the fetus' health.

· If you are overdue i.e. the pregnancy is over 40 weeks. If you are past the due date, NST can check for complications related to fetal heart rate and movement even if the pregnancy is healthy and low-risk.

Nonstress Test vs. Stress Test – What is the Difference?

So, what is NST in pregnancy, and how does it differ from a stress test? Know more:

· Nonstress Test: In an NST, the doctor measures the heart rate of the fetus. They also keep a notice of any changes in the same when the fetus experiences uterine contractions or when it simply moves. One of the benefits of NST is that it does not add any stress on the fetus or you. All you have to do is wear a monitor on your belly. Then you lay down and let the healthcare professional do the monitoring of the fetal heart rate.

· Stress Test: No, a stress test is related to measuring your blood pressure, heart rate, and oxygen levels. Here, the physician may ask you to pedal a stationary bike, walk on a treadmill, or perform some physical movements. All this while, monitors are attached to your chest. The stress test examines your heart’s response when it is put under stress, physically.

What Happens During an NST at Pregnancy?

Here is how an NST procedure may involve:

· The doctor may ask you to empty the bladder at first. Then they may ask you to lay down on an exam table or a reclining chair. Two elastic belts are then attached to your belly.

· There is a sensor on each belt. One of the sensors keeps a check on contractions. These contractions may even involve those that you do not feel.

· The other belt monitors the heart rate of the fetus. The heart rate is heard on a machine, the sound of which is like the heartbeat of the fetus during prenatal check-ups.

· The NST may go on for 30 minutes, in which the doctor keeps a record of the information collected on the fetus' health and heart rate.

· The information is presented in a chart form for the healthcare professional to analyze. After getting the necessary data, the doctor detaches the belts from your belly and discusses the NST results with you.

What Does the NST Result Tell About the Fetus?

If the fetus does not show movement during a nonstress test, it can indicate the fetus was asleep. In this case, the doctor may use a small noisemaker or buzzer (like a minute alarm clock) on your belly to wake the fetus up. Sometimes to wake the fetus, the doctor may ask you to eat a snack or drink something sugary during the NST. The NST result will be either reassuring (reactive) or nonreactive.

· Reactive NST: In this type of nonstress test result, the fetus heart rate may show an increase or acceleration when it experiences a contraction or it moves. It is a sign that the fetus is reacting to the movement. At least a couple of reactions from the fetus in a 20-minute test window is required to be called as a reactive NST result.

· Nonreactive NST: In this kind of nonstress test result, the fetus heart rate does not show any increase or changes with contraction or movement. The doctor can recommend additional tests to understand the reason why the fetus did not react during the NST. A nonreactive NST result means the fetus was extra sleepy, is not receiving sufficient oxygen, or the nonreaction was due to some medicines you are taking.

Extra Tests for the Pregnant Person After Undergoing NST

If a nonstress test shows a nonreactive outcome, it does not always mean the fetus is facing a complication or it is not viable. To learn more about the state of the fetus, the doctor can thereby ask to undergo additional tests.

· The initial step is to run a biophysical profile test that includes an NST with an ultrasound.

· Another diagnosis method is a contraction stress test. Here, the provider tries to check for the reaction of the fetus to contractions.

· You may have to take medicines provided by the doctor. These medicines cause uterine contractions, like those during labor. However, these contractions do not cause actual labor.

· After these tests, if the doctor notes risk of complications for the fetus, then closer examination is often needed, or an early delivery depending on the current pregnancy weeks.

Final Thoughts: NST and Its Role in Pregnancy Care

An NST is essential for pregnancy care. Here is a brief synopsis of what is NST in pregnancy to round up all the information till now. A nonstress test keeps a check on the fetus and its heart rate, usually its response to contractions or movements. A reactive result means the fetus can move and that shows with increased heart rate. A nonreactive result shows no increase in fetal heart rate or fetus movement at all.

But a nonreactive result for a nonstress test is possible if the fetus was asleep, did not receive enough oxygen, experiencing a complication, or if you have a medical condition as a cause of the lack of fetus response. After a nonreactive result, the doctor may order additional tests to monitor fetus well-being.

After the extra tests, the healthcare provider may come to determine why the fetus is not responding as required during an NST. The analysis will then help the doctor draw a diagnosis and suggest further steps like an earlier delivery, care for the mother or the fetus, attention to complications if any, and so on.