Clinical meaning
Electronic fetal monitoring (EFM) assesses fetal well-being by continuously recording the fetal heart rate (FHR) pattern and uterine contractions. The baseline FHR (normal 110-160 bpm) is regulated by the balance between sympathetic (accelerating) and parasympathetic (decelerating) autonomic nervous system inputs to the fetal heart. Moderate variability (6-25 bpm fluctuations) reflects intact fetal cerebral cortex-brainstem-cardiac conduction pathway integration and is the single most important indicator of fetal oxygenation. Accelerations (transient FHR increases of 15 bpm or more for 15 seconds or more) are reassuring reactive patterns. Decelerations are classified by their timing relative to contractions: early decelerations (mirror contractions, caused by fetal head compression activating vagal reflex — benign), variable decelerations (abrupt onset, caused by umbilical cord compression), and late decelerations (onset after contraction peak, caused by uteroplacental insufficiency with fetal hypoxemia — most concerning). The nurse interprets FHR tracings using the three-tier NICHD classification system (Category I normal, II indeterminate, III abnormal), implements intrauterine resuscitation measures for non-reassuring patterns, and escalates Category III tracings for immediate delivery.