What is a Non-Stress Test (NST)?
A non-stress test (NST) is a common prenatal test used to check on a baby's health. During an NST, the baby's heart rate is monitored to see how it responds to the baby's movements. The term "non-stress" refers to the fact that no stress is placed on the baby during the test.
Why is an NST Performed?
An NST is typically performed to assess the well-being of the fetus, especially in pregnancies that are considered high-risk. Conditions that might warrant an NST include maternal hypertension, diabetes, a history of fetal complications, or a pregnancy that has gone beyond 40 weeks. It is also used in cases where there may be concerns about the [amniotic fluid]( ) levels, [placental issues]( ), or [fetal growth restriction]( ).
How is an NST Conducted?
During the test, the mother will be asked to lie down, and a belt with sensors will be placed around her abdomen. These sensors measure the baby's heart rate and any [uterine contractions]( ). The mother may be asked to press a button each time she feels the baby move, so the correlation between movement and heart rate can be recorded. The test usually lasts about 20 to 30 minutes.
What Do the Results Mean?
The results of an NST are categorized as either reactive or non-reactive. A
reactive NST means that the baby's heart rate increased appropriately with movements, indicating good health. A
non-reactive NST means that the heart rate did not change as expected, which might warrant further testing such as a [biophysical profile]( ) or a contraction stress test.
What Happens if the NST is Non-Reactive?
If an NST is non-reactive, it doesn't necessarily mean there is a problem, but it does indicate the need for additional monitoring or tests. Further assessments might include an [ultrasound]( ) to check on the baby's movements, muscle tone, and levels of amniotic fluid. In some cases, the healthcare provider might recommend early delivery if they suspect the baby is in distress.
Are There Any Risks Associated with NST?
An NST is a non-invasive test and poses no risks to either the mother or the baby. However, it can sometimes lead to unnecessary anxiety if the results are non-reactive but the baby is actually healthy. It is important to discuss any concerns with your healthcare provider to understand the best course of action.
When Should an NST be Scheduled?
The timing and frequency of NSTs depend on the specific circumstances of the pregnancy. In high-risk pregnancies, NSTs might be scheduled as often as twice a week starting from 32 weeks of gestation. For other cases, it might be recommended less frequently or only under particular conditions.
Conclusion
Non-stress tests are valuable tools in the management of high-risk pregnancies and can provide important information about the baby's health. While a non-reactive result can be concerning, it is not definitive and often leads to further testing to ensure the well-being of the fetus. Always consult with your healthcare provider to interpret NST results and decide on the best course of action.
