Normal Fetal Heart Rate (FHR)

Baseline FHR

• Normal range: 110 - 160 beats per minute (bpm)
• This is assessed over a 10-minute window, excluding accelerations and decelerations

Abnormal Variants

Normal FHR Characteristics (on CTG/Cardiotocography)

Key Points

• Variability reflects the beat-to-beat variation and indicates a healthy, responsive autonomic nervous system
• Accelerations are a sign of fetal well-being and an intact central nervous system
• Early decelerations (mirror uterine contractions) are benign - caused by head compression
• Late decelerations (after the contraction peak) are non-reassuring - suggest uteroplacental insufficiency
• Variable decelerations are caused by cord compression

FHR Changes with Gestational Age

• Earlier in gestation, the baseline tends to be slightly higher (closer to 160)
• As the fetus matures, the vagal tone increases and the rate tends to fall toward the lower end of normal

Clinical Significance

• At least 2 accelerations of ≥ 15 bpm lasting ≥ 15 seconds within a 20-minute window
• This indicates fetal well-being

Note from ACOG/NICE guidelines: A normal (Category I) CTG trace shows a baseline of 110-160 bpm, moderate variability (6-25 bpm), no late or variable decelerations, and presence of accelerations.