Non-Stress Test

The Non-Stress test is one of the least invasive tests designed to monitor your baby's well being.  Usually recommended between 38 and 42 weeks, this test may be recommended if you have diabetes or high blood pressure, or if your baby shows signs of sudden growth rate declines--intrauterine growth retardation (IUGR), a drop in movements, or if he/she is post term (based on your provider's due date calculations). 

You will be hooked up to the electronic fetal monitor for an average of 20-60 minutes.  One of the belts around your abdomen will monitor your contractions (if any) while the second belt will measure your baby's heart rate.  Some non-stress tests will also have a button which you are to hold and push each time you feel the baby move.  A normal (or reactive) test result would be given, if:  

• your baby's heart rate increases at least twice in 20 minutes,

• the accelerations increase by at least 15 beats for 15 seconds,

• and when heart accelerations are related to his/her movements. 

An abnormal (or non-reactive) test result would be given if these criteria were not met.  Often if these criteria were not met, in the first 20 minutes, providers may ask you to drink a sugary drink, or may try to manually "wake" the baby by palpating your abdomen or exposing baby to a loud sound.  Then the baby will be retested. 

The risks associated with the Non-Stress test mostly come from possible incorrect interpretations of the test results.  If test results are not "normal"  according to the providers interpretations, further management (induction, cesarean sections) or more invasive tests (Stress Contractions Test/Oxytocin Challenge; Biophysical Profile) will be recommended--many of these containing risks of their own.  This test IS a method of electronic fetal monitoring;  statistically speaking, prolonged/routine electronic monitoring has been linked to higher cesarean rates without improving the outcomes of the baby. (See Electronic Fetal Monitoring)  Because of this, there are some studies which show that the non-stress test is not an effective method of determining the well being of the baby. 

The electronic fetal monitoring system does feature a doppler (a form of ultrasound)  for heart rate measurement-- it works like the hand held doppler used in a prenatal visit.  As of today, there have been no proven long term risks associated with this method of ultrasound but some say the long term effects are undiscovered.