Effects of maternal exercise on the fetal heart

Purpose: The benefits of exercise on cardiovascular health and disease prevention are known. Numerous studies have elucidated the safety of maternal exercise on the mother and birth outcome. Therefore, we aimed to examine the effect of maternal exercise during pregnancy on the cardiovascular health of the fetus. The hypothesis that exercise exposed fetuses have an improved autonomic tone was tested by measuring fetal heart rate and heart rate variability in exercise exposed and control fetuses at 28, 32, & 36 weeks GA. Methods: Mothers were classified as exercisers if they performed moderate intensity aerobic exercise at least 30 minutes 3 times per week. Mothers in the control category did not exercise. Utilizing a biomagnetometer, fHR was recorded for 18 minutes at each GA. After separating maternal and fetal heart rates, fetal R peaks were marked by computer and corrected manually. Data from 5 exercisers and 5 non-exercisers have been controlled for fetal gender and activity state. Results: Similar to an adult, fetuses exposed to maternal exercise have significantly lower HR than control fetuses at each GA. Measures of heart rate variability are significantly increased in exercise exposed fetuses at 32 wk GA relative to control fetuses. PSD and Poincare plots demonstrate evidence of a more mature autonomic innervation in exercise exposed fetuses. Conclusions: These results imply an exciting potential benefit of maternal exercise on fetal cardiac autonomic nervous system and a potentially positive prenatal programming effect which may prove to be the earliest intervention to prevent SIDS and cardiovascular disease.