A painless test of fetal well-being, generally performed after the 32nd week, that simultaneously records the baby's heart rate and the mother's abdominal contractions.
Indication
- Routine assessment of fetal well-being after the 32nd week of pregnancy
- Follow-up of high-risk pregnancies (gestational diabetes, hypertension, preeclampsia)
- History of complicated delivery in previous pregnancies
- Reduced fetal movements reported by the mother
- Suspected preterm labor
- Monitoring the fetus at the start and during labor
- Follow-up of post-term pregnancy (after the 40th week)
Preparation
- Eating before the test is recommended so the baby is more active
- Emptying the bladder before the procedure provides comfort
- Wear comfortable clothing suitable for lying on the side
- Pregnant women who smoke are advised to stop smoking before the test
How it's performed
- The mother is placed on the bed in a left-side or semi-sitting position
- Two sensors (transducers) are placed on the abdomen — one to record the baby's heart rate and another to record uterine contractions
- A button is given to the mother to indicate fetal movements
- The baby's heart rate, contractions, and movements are recorded simultaneously
- Recording usually lasts 20-40 minutes; the duration may be longer if the baby is asleep
- If needed, vibroacoustic stimulation or a change in position may be used to wake the baby
Post-procedure
- If the recording is reactive (normal), routine pregnancy follow-up is continued as recommended by the physician
- Reactivity is defined as at least 2 movements in 20 minutes accompanied by a 15 bpm acceleration lasting longer than 15 seconds
- If the result is non-reactive, the test may be extended, and a biophysical profile or Doppler may be planned
- In high-risk pregnancies, the NST is repeated at intervals determined by the physician
- In emergency situations, the result is evaluated together with other tests when considering early delivery
Risks
- There is no known significant risk to the mother or baby
- A false non-reactive result (when the baby is asleep) may occur and a repeat may be needed
- Wearing the belts for an extended period may be uncomfortable
- The result alone, outside the clinical context, does not provide a meaningful conclusion
FAQ
Is the NST test painful?
No. The sensors are secured to the abdomen with belts and do not cause pain or discomfort.
At which week does NST begin?
It usually begins after the 32nd week of pregnancy. In high-risk pregnancies it may be performed earlier. Frequency is determined by the physician.
How long does the test take?
It usually takes 20-40 minutes. The duration may be longer if the baby is asleep or if there is not enough movement.
What should I do if I notice that the baby is moving less?
If you notice a clear decrease in fetal movements, you should consult your physician without delay and have an NST.
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