Maternal heart rate variability and fetal behavior in hypertensive and normotensive pregnancies

The relation between maternal heart rate variability (HRV) and fetal behavior was examined in hypertensive and normotensive pregnant women. A total of 40 mother-fetal pairs (n = 20 normotensive mothers; n = 20 hypertensive mothers) at 33-41 weeks' gestation were observed using a standardized procedure lasting approximately 50 min. It included the following measurements: maternal beat-by-beat arterial blood pressure and HRV; spontaneous fetal heart rate (HR), body and breathing movements; and an estimate of amniotic fluid volume. The women in the hypertensive group had higher average body mass index (BMI) (33.7 vs. 28.8 kg/m2) than the normotensive group. In the normotensive group, there was no association between maternal HRV and fetal gestational age, HR, body or breathing movements. In the hypertensive group, maternal HRV measures of low-frequency, high-frequency, and total power were associated with fetal gestational age; also, there was an association between maternal autonomic modulation of HR and fetal spontaneous HR. These findings suggest that the maternal autonomic system influences fetal cardiac function in pregnancies complicated by hypertension.