Non-Stress Test (NST)
What Should I Expect?
• This test is usually done in the doctors office.
• You will need to be reclining or lying down for the test.
• You will have 2 belts strapped around your abdomen, one to measure the baby’s heartbeat and one to monitor for contractions. These will be attached to a fetal monitor.
• The test usually takes 20-30 minutes, but can take longer depending on the activity of the baby or if you are carrying multiples.
What is the Doctor Looking for?
The fetal heartbeat should be within the normal baseline range of 120-160. The baby’s heartbeat should accelerate in response to movement (these accelerations need to meet a certain requirement to be considered reactive). There should be no ominous signs, such as a deceleration in the heart rate. If you are less than 36 weeks, there should be no contractions. If your NST is not reactive, don’t panic. Usually, there is nothing wrong with the baby. Additional testing, such as ultrasound, or prolonged monitoring, will be ordered to be sure your baby is doing okay.
Why Am I Having an NST?
Non-stress tests are frequently done in high risk pregnancies to determine if the fetus is well enough for the pregnancy to continue or if delivery should be considered, but they are also done in routine pregnancies. Some of the most common reasons for an NST are:
- Decreased or no fetal movement
- Diabetes (gestational or pre-exisiting)
- Multiples (twins, triplets)
- High blood pressure
- Preterm labor or history of preterm delivery
- Post dates (> 40 weeks)
- Recurrent pregnancy loss
- Advanced maternal age
- Abnormalities in laboratory tests (such as an abnormal triple screen)
- Thyroid dysfunction