A nonstress test is a test that checks your baby's heartbeat patterns. It can show heart rate changes when the baby moves. It also shows changes when you have contractions, if you're having them. A fetal heart rate that speeds up when the baby moves means the baby is getting enough oxygen.
Why It Is Done
A nonstress test is often done when there is any question about how the baby is doing during later pregnancy. Some women with high-risk pregnancies are tested every week or twice a week in the third trimester.
Sometimes a nonstress test is done together with a fetal ultrasound. This is called a biophysical profile (BPP).
How To Prepare
If you smoke, you will be asked to stop smoking for 2 hours before the test. This is because smoking affects your baby's heart rate and movements.
How It Is Done
For the test, you will lie back on a padded exam table.
- Two elastic belts with sensors are placed across your belly. One sensor tracks your baby's heart rate with reflected sound waves (Doppler ultrasound). The other sensor measures how long your contractions are, if you are having any.
- You may hear your baby's heartbeat as a beeping sound. Or you may see it printed out on a chart.
- You may be asked to push a button on the machine when your baby moves or you have a contraction. This helps your doctor look at how your baby's heart reacts to movement and contractions.
- If there isn't much movement, it can be because the baby is asleep. If this happens during your test, the doctor or technician may try to wake the baby with a loud noise or by having you eat or drink something.
How long the test takes
- The test takes about 20 to 40 minutes. It depends on how quickly your baby becomes active.
After the test
- Before you leave, your doctor will tell you how your baby seems to be doing. You will also find out if more testing is needed.
- You will probably be able to go home right away. It depends on the reason for the test.
- You can go back to your usual activities right away.