Influence of maternal physical exercise on fetal and maternal heart rate responses

This study aims to determine if regular maternal physical exercise leads to measurable adaptations of the fetal autonomic nervous system (fANS) tested by fetal heart rate recovery time. A randomized controlled trial enrolled 131 pregnant women into two study groups, Exercise Group (EG) and Control Group (CG). All participants signed an informed consent, study was approved by the local Clinical Research Ethics Committee. Data was analyzed on 81 participants. EG participants (n = 43) received a supervised physical exercise program (PEP) three times a week from 10-12 to 36-40 weeks gestation. CG participants (n = 38) did not receive any supervised PEP. All women were tested between 34-36 weeks gestation using two walking tests of three minutes each at 40% and 60% maternal heart rate reserve. Resting fetal heart rate (FHR), FHR post-maternal exercise, and fetal recovery time (FRT) in minutes/seconds (m/s) were recorded. Resting FHR was similar between groups 140.88 +/- 9 EG vs 141.95 +/- 7.35 CG (p > .05). Difference in resting to post-maternal exercise FHR was statistically significant in fetuses from the CG (p < .05), however was not statistically significant in fetuses from the EG (p > .05). FRT was different between groups after both tests: 40% test: 2m15s +/- 3m19s EG vs 7m6s +/- 5m28s CG (p < .001); 60% test: 3m +/- 4m3s EG vs 9m25s +/- 7m33s CG (p < .001). There were no significant differences in maternal variables (p > .05), except for maternal recovery time after 40% test (p < .05). Influence of maternal exercise in FHR response still remains unclear. Further research is needed to elicit a former conclusion on the effects of maternal exercise on fANS. Overall, exercise during pregnancy is safe and not harmful for the cardiovascular system of the fetus.