A fetal non-stress test (NST) is an easy test which monitors the baby’s heart rate and any uterine activity you may be having… and how the baby responds during uterine activity. Because you (and the baby) are essentially relaxing, it is referred to as "non-stress."

During the NST, the Medical Assistant will ask you to lie on a reclining chair. At this time she will affix 2 sensors to your abdomen with a soft strap – the first (top of the fundus) will monitor any uterine contractions or activity and the second (lower part of the abdomen) monitors the baby’s heart rate. Both sensors will record on a strip of tracing paper so the physician or nurse practitioner can see how your baby (and your uterus!) are behaving over a period of approximately 20 minutes.

Just like adults, babies heart rates go up and down with activity (normally between 120-160 beats per minute), however, if your baby is inactive or asleep during the test, there may not be the ‘waves’ or changes in the heart rate that we typically look for on the recording strip. If this happens, we will give you a cold, sugary fruit drink which usually ‘wakes’ the baby up - and will hopefully provide the variance of heart rate we look for in a reassuring (reactive) strip.

NST’s are typically performed weekly after 28 weeks of pregnancy in the following cases:

  • Advanced maternal age (over 35)
  • Underlying medical conditions such as Type I Diabetes, heart disease, high blood pressure, etc. 
  • Post-term pregnancies
  • Complications with a previous pregnancy
  • Decreased fetal movement
  • Fetal growth or developmental concerns
  • Low amniotic fluid