A non-stress test or NST is a very common and painless test done in your health care provider’s office to verify that your baby is doing well.
It is done once or twice a week starting, at the soonest, at 28 weeks if you are having a high risk pregnancy. It is also done frequently if the baby is not moving much.
It involves having a machine tracing, on a piece of graph paper, the changes of the baby’s heart rate over a 20 to 30 minute period. When the baby moves, the heart rate will usually go up, and this is called an acceleration.
If there two or more specifically patterned accelerations in your baby’s heart rate, the test is satisfactory and called “reactive.” If you have a reactive NST, the baby is doing well and the chance of something “bad” happening to your baby over the following week is small. If these accelerations are not seen, the NST is called “non-reactive” and your health care provider will do further testing to ensure that your baby is doing well.
Often an ultrasound to look at the amniotic fluid level will be done the same day as the NST in order further ensure the baby’s health.