Non-Stress Test (NST)

• NST is a prenatal screening test that measures the fetal heart rate (FHR) in response to fetal movements



• NST can assess fetal well-being and identify fetal hypoxia or distress
• NST is usually performed after 28 weeks of gestation or earlier if there are risk factors such as diabetes mellitus, hypertension, intrauterine growth restriction (IUGR), .
• NST involves placing two belts with sensors on the pregnant person’s abdomen: one to monitor the FHR and one to monitor the uterine contractions
• NST requires the pregnant person to press a button whenever they feel the fetus move
• NST is usually done for 20 to 40 minutes or until at least two fetal movements are recorded
• NST is interpreted as reactive or nonreactive
• A reactive NST means that the FHR increases by at least 15 beats per minute for at least 15 seconds twice or more in a 20-minute period
• A reactive NST indicates adequate fetal oxygenation and normal fetal neurological function
• A nonreactive NST means that the FHR does not meet the criteria for a reactive NST
• A nonreactive NST may indicate fetal hypoxia, distress, sleep, medication effect, or neurological abnormality
• A nonreactive NST requires further evaluation such as a biophysical profile (BPP) or a contraction stress test (CST)
• NST has no risks or complications for the pregnant person or the fetus