Fetal Heart Rate Variability Following An Acute Bout Of Maternal Exercise During Pregnancy

PURPOSE: It is well known that the fetal environment influences the development of the fetus’ nervous system. For example, pregnant mothers who regularly engage in aerobic exercise give birth to babies with greater brain maturity (May et al. 2014; LeMoyne et al. 2013). This suggests that the autonomic nervous system of the fetus may be stimulated while the mother is exercising. The purpose of this study was to examine fetal cardiac-autonomic function following an acute bout of maternal exercise. METHODS: Electrocardiograms were placed on a group of 10 pregnant women in order to detect fetal cardiovascular activity. Participants then completed 30-minutes of cycling at 50% of their maximum oxygen consumption. Fetal Heart Rate (HR) and Heart Rate Variability (HRV) were analyzed for 5 minutes before the start of exercise and for a period of 10 minutes immediately after the exercise session. RESULTS: A series of one-way repeated measure ANOVAs revealed that spectral power of fetal HR was significantly greater immediately following exercise cessation, as indicated by increased absolute power at very-low (VLF), low (LF), intermediate (intF) and high frequencies (HF) (ps<0.05). Furthermore, fetal HRV was significantly greater immediately following exercise cessation, as indicated by an increase in the standard deviation of beat-to-beat intervals (SDNN/NN) and root mean square standard deviation (RMSSD/NN) (ps<0.05). These modifications returned to pre-exercise baseline within 10 minutes of exercise cessation. CONCLUSIONS: An acute bout of exercise during pregnancy leads to significant alterations in multiple fetal HRV parameters, suggesting a modification in fetal cardiac-autonomic activity. The current findings add to our knowledge regarding the influence of maternal exercise on fetal cardiac-autonomic function, reaffirming the benefit of maternal exercise on fetal health.