Maternal Heart Rate and Heart Rate Variability During Pregnancy and Exercise Training

Exercise in non‐pregnant women increases parasympathetic control resulting in lower resting heart rates (HR) and increased heart rate variability (HRV). This is important given the relationships between pregnancy complications (hypertension, pre‐eclampsia and gestational diabetes) and altered autonomic control. This study tested the hypothesis that maternal exercise throughout gestation alters maternal cardiac autonomic control as indicated by changes in HR and HRV. We used magnetocardiography to record maternal HR between 28 and 32 wks GA from 20 women who exercised regularly (>30 min aerobic activity, 3 times per week) and 19 women who did not exercise during pregnancy. R‐R intervals were used to determine HR and HRV. HR (82.9 + 9.1 vs 90.4 + 9.9 bpm; F=6.2(1,37);p<0.05) was lower, pNN50 was greater (16.3 + 19.4 vs. 6.1 + 6.0; F= 4.7(1,37);p<0.05), and there was a trend of higher SDNN (p=0.05) indicating increased parasympathetic control in the exercise relative to the non‐exercise group. LF/HF, an index of sympathovagal balance, was lower (0.55 + 0.36 vs. 0.82 + 0.53; F=4.3(1,37), p<0.05) in the exercise group. Indices of parasympathetic control are altered in women who exercise regularly throughout their pregnancy. Therefore, exercise can be used as an intervention to decrease the risk of pregnancy complications associated with increased sympathetic input. Research supported by: KCUMB and Hoglund Brain Imaging Center funds