Key Concepts
Introduction
The fetal heart rate (FHR) is regulated by the autonomic nervous system. The sympathetic nervous system increases heart rate, while the parasympathetic (vagus nerve) decreases it. Normal baseline is 110-160 bpm. Variability reflects intact CNS function: absent (no fluctuation: ominous), minimal (<5 bpm), moderate (6-25 bpm: reassuring, indicates intact neurological pathway), and marked (>25 bpm). Accelerations (≥15 bpm above baseline for ≥15 seconds) are reassuring and indicate fetal well-being. Decelerations are classified as Early (head compression, mirrors contractions), Late (uteroplacental insufficiency, begins after contraction peak), and Variable (cord compression, abrupt onset/offset with varying shape). On the exam, writers often pair stable-sounding options with unstable data—notice the mismatch before you commit. If the stem names a license or role, reread that line; scope errors are classic trap answers even when the clinical topic is familiar. Run a 60-second scan: breathing work and oxygenation, perfusion and end organs, neuro baseline, likely infection sources, and devices that can fail quietly. When two answers feel partly right, pick the one that reduces imminent harm and matches orders for the role you were given. Train...