Amount of Physical Activity in Pregnancy and Infant Heart Outcomes

Linda E May and Richard R Suminski

Purpose: Our previous findings demonstrated that the amount (dose) of maternal physical activity during pregnancy was associated with changes in fetal heart autonomic control, similar to an adult exercise trained response. The purpose of this study was to determine if the dose of maternal physical activity during association persists after birth.

Methods: We analyzed 43 maternal-infant pairs. Since the majority of measures were not normally distributed, the correlations between infant heart rate (HR) and HR Variability (HRV) metrics and maternal physical activity measures were assessed by the Spearman correlation coefficient. The Spearman procedure also was used to examine relationships among the physical activity variables.
Results: The median values for maternal physical activity duration were 1140 min (~90 min/wk), for energy expenditure 6,635 kcal, and the intensity was 5.4 kcal.min-1 (Table 1). Based on the average maternal weight, average intensity is near the cut-off (6.0 kcal.min-1) for moderate and vigorous intensity level of physical activity. There was a significant positive correlation between the duration of maternal physical and infant Low Frequency (LF) HRV power (p=0.02), as well as the amount of energy expenditure (i.e. calories burned) in physical activity with infant short-term HRV (RMSSD, p=0.03), LF power (p=0.01) and high frequency (HF) HRV power (p=0.03).

Conclusion: The amount of time and energy expended during physical activity during gestation positively influences the development of neonatal cardiac autonomic control. Coupled with our previous findings of positive fetal dose associated with physical activity during pregnancy suggests, the prenatal period may be the earliest time at which the cardiac health of infants can be positively influenced to decrease risk of heart disease.