THE INFLUENCE OF EXERCISE BEFORE AND DURING PREGNANCY ON OFFSPRING HEART FUNCTION AND DEVELOPMENT

Abstract

Maternal exercise during pregnancy is quickly becoming a trend that has been shown to have benefits for fetal and infant development (e.g. heart health and development). Most studies examining the influence of exercise during pregnancy on infant outcomes have enrolled women that were previously active and the exercise during pregnancy was self-reported. Therefore, we do not know if changes in infant heart health and development, as measured by heart rate (HR) and heart rate variability (HRV), occur from activity prior to pregnancy or an exercise during pregnancy. PURPOSE: The purpose of this study is to determine the effects of exercise before and during pregnancy on infant heart health at one month of age, by measuring infant HR and HRV. We hypothesized that we would find that women participating in (1) Preconception physical activity will have infants with improved cardiac health; (2) exercise during pregnancy will have infants with improved cardiac health; and (3) Exercise during pregnancy will be the greatest predictor of infant cardiac health at 1 month after birth. METHODS: Participants completed a questionnaire to determine Physical Activity (PA) before pregnancy; the Active before pregnancy group is defined as women who participated in 150 minutes of moderate intensity PA throughout pregnancy, while the Inactive before pregnancy group were women that did not meet this criteria. During pregnancy, women were randomized to supervised aerobic (Active during pregnancy) or non-exercise groups (Inactive during pregnancy); the exercise intervention occurred from enrollment (13-16 weeks gestation) until delivery. Women participated in supervised exercise for three, 50-minute moderate intensity sessions per week. Non-exercisers (control) did not participate in exercise, but were regularly contacted. Heart rate (HR) and heart rate variability (HRV) were recorded in infants one-month after birth. Measures of Infant HRV included for analysis were SDNN, RMSSD, LF, HF, and LF:HF ratio, which are representative of improved sympathetic, parasympathetic, and overall cardiac autonomic nervous system control. Data were analyzed using t-tests between active and inactive women before pregnancy or exercisers and non-exercisers during pregnancy as well as ANCOVA to determine the greatest predictor of infant HR and HRV. Participants (n=24) were similar in age, body mass index (BMI), and parity. There were 14 male and 10 female infants born. RESULTS: There are no differences in infant heart measures when comparing active to inactive women before pregnancy. Infants of participants who exercised during pregnancy had significantly lower average HR (p=.02) in the active state relative to infants of women in the non-exercise group. Additionally, infant HR is higher Inactive/Inactive (I/I) group compared to infants of women in the Active/Active (AA) group and infants from women of the Inactive/Active (IA) group. Three regression models demonstrate trends or significance for exercise during pregnancy to predict infant resting HR. CONCLUSIONS: Based on the updated exercise guidelines from the American Congress of Obstetrics and Gynecology (ACOG), the results of this present study suggest that exercise during pregnancy at recommended levels is associated with lower infant heart rates in comparison to those who did not exercise during pregnancy. Our results provide support to continue or to begin a moderate intensity aerobic exercise during low-risk pregnancies in order to improve offspring heart health. Although further research is needed, these data support that exercise during pregnancy may be one of the earliest interventions to improve infant heart health and potentially decrease future risk of heart disease.