Prenatal non-stress test, popularly known as NST, is a method used to test fetal wellbeing before the onset of labor. A prenatal non-stress test functions in overall antepartum surveillance with ultrasound as a part or component of the biophysical profile. The presence of fetal movements and fetal heart rate acceleration is the most critical feature of the non-stress test. It is a non-invasive test used for the surveillance of high-risk pregnancies when the fetus is judged clinically to be at risk for hypoxemia or increased risk of death. Trained and certified nurses, midwives and physicians should read and interpret the non-stress test. The NST readings are as reactive and none reactive. The non-stress tests can initiate at 26 to 28 weeks. The NST is reactive from 32 weeks. The Non-Stress Test (NST) is an assessment tool used from 32 weeks of gestation to term to evaluate fetal health through the use of electric fetal monitors that continuously record the fetal heart rate (FHR). The test is used to determine if a fetus is at risk for intrauterine death or neonatal complications, usually secondary to high-risk pregnancies or suspected fetal hypoxemia. The frequency of use is based on clinical judgment, but is common because it is non-invasive and presents a low maternal and fetal risk; however, the test does not hold predictive value and only indicates fetal hypoxemia at time of the test. The presence of fetal heart rate acceleration with fetal movement is the principle behind the non-stress test. The NST recognizes the coupling of fetal neurological status to cardiovascular reflex responses. It is one of the factors that tends to disappear earliest during progressive fetal compromise. Interpretation of the nonstress test follows a systematic approach to include: the baseline fetal heart rate, baseline fetal heart rate variability, presence of accelerations, decelerations, and contractions.