Role of Non-Stress Test (NST) in Pregnancy 1. Assess Fetal Oxygenation and Well-Being NST evaluates fetal heart rate (FHR) patterns in response to fetal movements. A reactive NST suggests adequate fetal oxygenation and intact autonomic nervous system. ✅ 2. Screening Tool for Fetal Hypoxia Early detection of chronic fetal hypoxia in at-risk pregnancies. Helps decide whether further testing or delivery is needed. ✅ 3. Monitoring High-Risk Pregnancies NST is commonly used in conditions such as: Diabetes mellitus Hypertension / preeclampsia Fetal growth restriction (IUGR) Post-term pregnancy (40 weeks) Decreased fetal movements Oligohydramnios Multiple pregnancy Rh isoimmunization ✅ 4. Guide Timing of Delivery Nonreactive NST may prompt: Biophysical profile (BPP) Contraction stress test Early delivery if indicated ✅ 5. Safe and Non-Invasive Monitoring Uses external Doppler; no risk to mother or fetus. Can be repeated frequently. 🩺 Interpretation Reactive NST: accelerations of fetal heart rate (15 bpm for 15 sec) within 20 minutes → Normal / reassuring Nonreactive NST: No adequate accelerations in 40 minutes → requires further evaluation. ⭐ Key Points for Exams NST becomes reliable after 32 weeks (fetal autonomic maturity). First test done in most high-risk pregnancies. Part of biophysical profile.