Pregnancy Testing

Non-Stress Test

A non-stress test (NST) is an evaluation of your baby's overall health. It compares your baby's heart rate patterns in response to movement to the generally accepted normal patterns. You will want to see accelerations, which means your baby's heart rate increases when he moves. NST is an easy procedure that can be completed in 20 minutes during a regularly scheduled appointment. It is also an inexpensive test which makes it popular.

What you need to know

There is a high rate of false-positives which means a large percentage of mother's are told their baby may be in trouble when nothing is wrong. The most common reason for a non-reactive NST is that the baby is sleeping.To prevent false negatives, several techniques have been used to stimulate the baby. You may be asked to drink Orange Juice, have someone shine a light on your abdomen, press your abdomen to stimulate movement or use vibroacoustic stimulation (noise).

Baby's are most likely to be non-reactive when the mother is lying directly on her back. Instead, sit or recline in a chair with your body tilted slightly to the left.

To be considered non-reactive, your baby must have less than two accelerations in a forty minute test.

Procedure

You will be given a reclining chair to relax in, and asked to sit with a slight left tilt. An electronic fetal monitor will be positioned so both your baby's heart rate and movement can be recorded on the strip. If your baby's movements cannot be detected, you may be asked to press a button when your baby moves. It is generally over in 20 minutes, but can take longer.

References

Alus, M., Okumus, H., Mete, S., and Guclu, S. (2007). The effects of different maternal positions on non-stress test: an experimental study. Journal of Clinical Nursing 16(3): 562-8.