Aerobic exercise during pregnancy influences fetal cardiac autonomic control of heart rate and heart rate variability

Abstract 

Background

Previous studies using ultrasound technology showed that fetal heart rate (HR) may be responsive to maternal aerobic exercise. Although it is recognized that cardiac autonomic control may be influenced by the intrauterine environment, little is known about how maternal exercise affects fetal heart development.

Aims

This study tested the hypothesis that regular maternal exercise throughout gestation influences fetal cardiac autonomic control of HR and heart rate variability (HRV) when compared to fetuses of non-exercising women.

Study design

Magnetocardiograms (MCGs) were recorded using a dedicated fetal biomagnetometer at 28, 32 and 36weeks gestational age (GA) from 26 regularly exercising (>30min of aerobic exercise, 3× per week) and 35 healthy, non-exercising pregnant women. Fetal MCG was isolated and normal R-peaks were marked to derive fetal HR and HRV in the time and frequency domains. We applied a mixed-effects model to investigate the effects of exercise, GA and fetal activity state.

Results

At 36weeks GA, during the active fetal state, fetal HR was significantly lower in the exercise group (p=<0.0006). Post-hoc comparisons showed significantly increased HRV in the exercise group during the active fetal state at 36weeks GA for both time and frequency domain measures.

Conclusion

These results indicate that regular maternal exercise throughout gestation results in significantly lower fetal HR and increased HRV.

Keywords: Autonomic nervous system, Fetal heart rate, Heart rate variability, Maternal exercise, Magnetocardiology