Fetal Non-Stress Test (NST)


Pregnancy at every stage has a risk of getting terminated. During early pregnancy there is less of physical stress. But as pregnancy goes further a lot of physical stress due to weight of baby and pregnancy water builds up. It is important to monitor whether you are capable of undergoing the excruciating pain and struggle of natural delivery. If pregnancy has complications then doctors advice a C section or cesarean surgery. Fetal Non-Stress Test (NST) is for women who have a high risk of life during parturition. A pregnancy non stress test monitors this ability to deliver naturally. It is a non invasive test.

What is a Fetal Non-Stress Test (NST)?

A non-stress test during pregnancy is a method for checking whether the baby is healthy and is growing well. Pregnancy non-stress test measures the heart rate of fetus and response to movement. It also determines whether the baby has enough oxygen reaching to her. Fetal non stress test during pregnancy is done after 28 weeks of pregnancy pass. The non stress pregnancy test is a third trimester non invasive pregnancy test.

Fetal Non-Stress Test (NST) | Pregnancy Stress Test
Fetal Non-Stress Test (NST) | Pregnancy Stress Test

Most Common 15 Reasons for taking the Fetal Non-Stress Test

  1. Gestational diabetes: If mother has gestational diabetes then there can be a lot of complications during labor. The non stress pregnancy test ensures that the baby is healthy and will bear the high level of strain during delivery.
  2. Preclampsia: Preclampsia is the condition when the pregnant woman has a very high blood pressure. It is also termed as toxemia. There is swelling in limbs and urine has protein. This can lead to life threatening bleeding during parturition. Parturition is the act of delivering a child. A pregnant woman having Preclampsia needs to undergo pregnancy non stress test.
  3. Gestational age complications: If the fetus is smaller than the gestational age then the pregnant woman has to undergo non stress test during pregnancy. This shows that the baby is not growing well and is not strong enough to take the challenging delivery struggle.
  4. Amniocentesis: Amniocentesis is the test for determining the gender of baby. It is an invasive pregnancy gender test. Before taking Amniocentesis it is important to take non stress pregnancy test. Third trimester amniocentesis is for checking lung function of the baby. Any invasive pregnancy test can cause infections and other diseases. Thus it is important to take non stress pregnancy test to monitor baby’s heart rate.
  5. Delayed parturition: If your baby stays in your womb for long even after expected date you need to take non stress pregnancy test. This is because there are hazardous complications associated with overdue delivery. If your baby is still inside the womb two weeks past delivery date then a non stress test during pregnancy is a must.
  6. Limited movement of baby: If your baby doesn’t move much then your doctor will suggest a non stress pregnancy test. This is because it indicates that there are issues with your pregnancy.
  7. Twin pregnancy: Doppler heart beat twin pregnancy test actually detects whether you’ve twins. Pregnancy non stress test tests whether the twins are healthy.
  8. Positive Rh factor test: Rh factor is a marker present on cells that determines your blood group. If a pregnant woman is Rh positive she will form antibodies against a Rh negative blood. Rarely your own fetus may have Rh negative blood group. This can cause a condition called Erythrocytosis Blastosis. In this baby’s cells burst because the mother produces antibodies against them. There are immunosuppressive drugs that can prevent this health condition. Non stress test pregnancy will help check whether the baby is withstanding the treatment or not.
  9. Amniotic fluid quantity: If you don’t have enough volume of Amniotic fluid then you need to take the non stress pregnancy test. Pregnancy stress tests are for babies that have high quantities of Amniotic fluids. The fluids create a pressure equally distributed in all directions.
  10. Abnormal results of other prenatal tests: Women have to take many prenatal tests like chorionic villus sampling, biophysical profile and glucose tolerance test. If any of the tests have abnormal results then a non stress pregnancy test is advisable. Any complications that can affect your baby’s health are reasons for taking non stress test during pregnancy.
  11. Umbilical cord problems: There are chances that the umbilical cord may intertwine and suffocate your baby. The non stress test pregnancy will predict a less active baby and thus any such problems.
  12. Placenta problems: A low lying placenta can be problematic during delivery. Non stress test during pregnancy will determine the severity of the situation.
  13. Birth defects in Baby: Chromosome defects can cause birth defects in baby. Any such birth defects in baby require a non stress test pregnancy.
  14. You have a history of miscarriage in the second trimester: In case you lost your previous baby during the second trimester due to inexplicable reasons then NST will help prevent such incident.
  15. External cephalic version: Cephalic version is the procedure for a breech baby. Pregnancy non stress test is also performed while this procedure.

When do you take pregnancy non stress test?

The non stress pregnancy test is not your choice. Only experts can perform a pregnancy non stress test. It is a third trimester pregnancy test. You can expect your doctor to recommend you to take non stress test during pregnancy by the 28th week. Why is a pregnancy stress test is required? A pregnancy stress test will determine any problems with the baby such as low activity. A baby’s heartbeat is around 160 beats per minute. Non stress test Pregnancy detects your contractions during baby’s movements. This test determines how well your baby responds to external stimuli.

How is pregnancy non stress test (NST) done?

The Fetal Non-Stress Test is non invasive. A buzzer placed on your baby bump awakes the baby. Then using a doppler the heartbeat of fetus is monitored. What happens during non stress pregnancy test? Non stress test in pregnancy involves tieing two belts around your baby bump.

  1. You’ll have to eat something and take a glass of fizzy energy drink. This will provide enough energy for your baby to move. You’ll have to use the bathroom so that your bladder is empty and also because you’ll not be allowed to move for the next 40 – 60 minutes.
  2. Next you’ll lie down on your left side to avoid hampering blood flow. Your doctor will tie two belts around your baby bump. One will monitor the heart beat of fetus and other will record your uterine contractions.
  3. You’ll be doing a job too. You will hold a buzzer kind of device that you have to press every time you feel your baby moves.

Whenever you will press the buzzer it will register the heartbeat of baby at that time. Another stretchable belt will record your uterine contraction intensity. It will determine how you labor will induce. Labor induces due to baby’s movements. When the baby starts moving too rapidly it sends a signal to brain to induce labor. The ratio of contractions to baby’s movements will help doctor decide whether natural delivery is ideal for you.

How long does the non stress pregnancy take?

The non stress test during pregnancy takes about 20 – 40 minutes.

Are there any risks associated with NST?

The pregnancy non stress test is non invasive and has no risks and side effects.

How the non stress test during pregnancy works?

Non stress test during pregnancy works on the principle that enough oxygen is essential for normal fetal heartbeat. If the oxygen supply to the baby is adequate then her response will be reactive to the external movement. Non stress test Pregnancy simply checks the fetal heartbeat and oxygen availability. Pregnancy non stress test is only done after 28 weeks of gestation. Before 28 weeks the baby is not capable of responding to external stimulus.

Non-stress pregnancy test results interpretations

Non stress test during pregnancy results are namely reactive and non reactive.

  1. Reactive NST pregnancy result: The reactive result means that your baby is moving actively. He or she is reactive to any stimuli given. It shows that your baby heartbeats at the right pace. The oxygen supply to your baby is ample.
  1. Non reactive NST pregnancy result: A non reactive result of pregnancy stress test is negative. This shows that your baby isn’t moving enough within the 40 minutes span. It does not mean that your baby is at risk of any disease. It could be that he is still asleep. You could be taking certain prescriptions that reduce the activity of baby. Poor oxygenation is the major reason for nonreactive non stress test.If you get a non reactive result of non stress test during pregnancy then your doctor might recommend a pregnancy stress test. Other prenatal tests like biophysical profile may be thought about.

Cost of non stress test during pregnancy is around 185$ to 286$ depending on the hospital. You don’t need to bother yourself about when to take a pregnancy stress test. However, if you sense that your baby moves very less, then talk to your doctor about it.


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