Nonstress Test

A nonstress test (NST) is a safe and painless test given during pregnancy. The test measures the heart rate of your developing baby as the baby moves or when you have contractions in your uterus. Your uterus is the place where your baby grows during pregnancy.

In most healthy babies, the heart rate, also known as the fetal heart rate, increases during movement. If your nonstress test results showed that the fetal heart rate was not normal, it may mean that your baby is not getting enough oxygen. If this happens, you may need more testing or treatment.

In some cases, your health care provider may want to induce labor so you can deliver your baby. Your provider will give you medicine or use other methods to start labor before it begins naturally.

Why this test is done

You may need this test if:

• Your baby doesn't seem to be moving as much as usual.
• Your pregnancy is overdue (at 42 weeks or beyond).
• You have a chronic medical condition that makes your pregnancy high risk, such as high blood pressure, diabetes, heart disease, or a clotting disorder.
• You had complications in a previous pregnancy.
• Your blood is Rh negative, and your baby's is Rh-positive, which is called Rh incompatibility. This condition can cause your immune system to attack your baby's red blood cells.
• You are having more than one baby (twins, triplets, or more).

How to prepare

You don't need to do any special preparations for a nonstress test. However, your provider may ask you to go to the bathroom to empty your bladder before the test.

Other names for this test

fetal nonstress test, NST