The Non-Stress Test (NST) is a common procedure that may be offered to you in pregnancy. It is done to be sure that everything is okay with your baby. It is sometimes recommended in the later stages of pregnancy, mostly after 32 weeks.
What Is an NST?
The NST measures your baby’s heart rate continuously. “Stress” would be checking on baby’s heart rate while inducing contractions, like with Pitocin. “Non stress” is without inducing contractions. The goal is to check how your baby’s heart rate responds to their movements, which can indicate how well they are receiving oxygen and nutrients through the placenta. We would like to see that fetal heart rate going up and coming down to what we call the baseline.
Why Is an NST Done?
An NST is typically performed if your healthcare provider wants to ensure your baby is healthy, particularly in situations such as:
- High-Risk Pregnancy:
- Conditions like diabetes, high blood pressure, or a history of complications may require extra monitoring.
- Decreased Fetal Movements:
- If you notice your baby is moving less than usual, an NST can provide reassurance.
- Post-Term Pregnancy:
- After 40-41 weeks, the NST helps ensure the baby is still thriving.
- Multiple Gestations:
- Monitoring twins or other multiples – they may require additional testing to assess their health.
- Placental Concerns:
- If there are worries about placental function or reduced amniotic fluid levels.
How Is an NST Performed?
The procedure is simple and typically takes about 20-40 minutes:
- Getting Comfortable:
- You’ll lie back in a reclined chair or bed, and two sensors are placed on your abdomen using elastic belts.
- Measuring Heart Rate:
- One sensor monitors the baby’s heart rate, while the other checks for uterine contractions.
- Tracking Movements:
- You may be asked to press a button when you feel the baby move. This helps correlate the baby’s movements with their heart rate.
- Interpreting Results:
- A healthy baby’s heart rate should increase when they move, indicating good oxygen levels and well-being.
Interpreting NST Results
- Reactive NST (Normal):
- Baby’s heart rate increases at least twice during the test, staying elevated for at least 15 seconds.
- Indicates good health and oxygenation.
- Non-Reactive NST:
- Baby’s heart rate does not meet the criteria for a reactive result.
- May require additional testing, such as a biophysical profile (BPP) https://montanaobgyn.com/biophysical-profile-bpp-a-window-into-babys-well-being/– or contraction stress test (while contractions are being induced), to confirm the baby’s condition.
Other Tidbits About the NST
- Painless and Safe:
- The NST is completely non-invasive and safe for both mom and baby.
- Timing:
- Usually performed after 32 weeks of pregnancy when the baby’s heart rate and activity patterns are more predictable.
- Frequency:
- High-risk pregnancies may require weekly or biweekly NSTs, depending on your provider’s recommendations.
- False Alarms:
- A non-reactive result doesn’t always mean there’s a problem. The baby might simply be sleeping or less active during the test.
The Bottom Line
The Non-Stress Test is a valuable tool for assessing your baby’s well-being and providing peace of mind during pregnancy. It’s quick, safe, and effective in identifying potential concerns, ensuring your baby gets the care they need before delivery. Always discuss your results and any questions with your healthcare provider.
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