A nonstress test is a type of test done during pregnancy. It measures the heart rate of the unborn baby (fetus) in response to its movements. In most cases, the heart rate of a healthy baby increases when the baby moves. The nonstress test is usually done in the last trimester of pregnancy.
Your healthcare provider may advise a nonstress test in any of these cases:
There are no risks to either the mother or baby during a nonstress test.
You don’t need to do any special preparation before the test.
The test may be done in a special prenatal testing area of the hospital. Or it may be done in your healthcare provider's office.
The procedure may vary, but a typical nonstress test may go like this:
In some cases, the testing occurs during a baby’s sleep cycle, when there is little fetal movement. A special sound (acoustic) device may be used to awaken the baby. It is placed against the mother's belly and makes a noise like a buzzer. This is not harmful to the baby. But it may help a sleepy baby become more active. Your baby may also awaken if you eat or drink.
The provider will remove the belt and transducer and wipe off the gel. You will be told the results of the test.
Test results of the nonstress test may be:
A nonreactive nonstress test doesn’t always mean your baby has a problem. The baby may simply be asleep. Or it may be nonreactive because the baby is immature. It’s common for preterm babies to have nonreactive nonstress tests, especially before 28 weeks. Your healthcare provider will tell you if you need other prenatal testing.
Before you agree to the test or the procedure make sure you know: