SPECTRAL-ANALYSIS OF ANTEPARTUM FETAL HEART-RATE-VARIABILITY FROM FETAL MAGNETOCARDIOGRAM RECORDINGS

Fetal heart rate variability was derived from fetal magnetocardiogram recordings in ten subjects at gestation ages 32-38 weeks. Maternal int erference was negligible and R-wave detection was highly reliable. Osc illations suggestive of respiratory sinus arrhythmia (RSA) were promin ent in many of the heart rate tracings. Spectral analysis was used to quantify heart rate variability and to examine the influence of the RS A-like oscillations on heart rate variability. The oscillations were a ssociated with increased power in the frequency range 0.4-1.0 Hz (P le ss than or equal to 0.05). Magnetic recording appears to offer signifi cant advantages for investigation of beat-to-beat fetal heart rate thr oughout the latter stages of pregnancy.