Fetal Nonstress Test (NST): What It Is & Why It's Performed

Doctors perform a fetal nonstress test (NST) during pregnancy to check on the health of the baby and make sure it is progressing properly.

Features

• For an NST, the doctor applies equipment to the mother's abdomen to monitor the fetus's heart during resting and active periods, and to time contractions, according to the American Pregnancy Association.

Necessity

• Usually, doctors only deem this test necessary for mothers with potentially risky births coming up, typically because the mother has a condition such as diabetes, or has failed to give birth within a normal time frame.

Misconceptions

• Occasionally the doctor records no movement in the child. This does not necessarily indicate a problem as the baby has probably just fallen asleep. The nurse will wake the baby with a light buzzing sound if a light meal or drink does not stimulate activity.

Normal Result

• At least twice during the 20-minute to 60-minute procedure, a healthy fetus heart should beat at least 15 times per minute faster in its active state than in its resting state .

Side Effects

• The NST is perfectly safe for the fetus and the mother, hence the name "non-stress." Typically, this test does not occur before the 28th week of pregnancy because fetuses are generally too underdeveloped prior to that time.