Effects of Maternal Exercise on Fetal Breathing and Hiccups

Abstract

The hypotheses that fetal breathing and hiccups alters fetal heart rate and that exercise exposed fetuses have increased breathing activity compared to non‐exercise exposed fetuses were tested utilizing a biomagnetometer at various gestational ages. 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 partake of a regular exercise regime. We analyzed fetal breathing movements and hiccups waveforms for frequency, duration, and cycles per episode; heart rate minimum, maximum, and mean; sympathetic and vagal tone, and fetal activity state. Average heart rate during breathing movements relative to non‐breathing periods was similar. Breathing frequency increases at 32 weeks GA. Exercise exposed fetuses show an increased frequency in breathing compared to controls. Exercise exposed females have the greatest increase in frequency relative to exercise exposed males, or control males and females. Fetal heart rate decreases during episodes of hiccups which corresponded with decreased sympathetic tone and increased vagal tone. These findings suggest a potential benefit of maternal exercise on fetal diaphragm development. These data suggest a potentially positive prenatal programming effect which may prove to be the earliest intervention to prevent SIDS.