Exercise during pregnancy (frequency, intensity, type, time, volume): birth outcomes in women at risk of hypertensive disorders of pregnancy

BACKGROUND: Hypertensive disorders of pregnancy (HDP) hold negative health implications for mothers and offspring. While the beneficial influence of prenatal exercise on reducing HDP risk has been previously shown, there is a lack of specific information on the effect on birth outcomes in at-risk women, and in-depth analysis of appropriate exercise dose is lacking. OBJECTIVE: We aimed to elucidate the effects of exercise training FITT-V (frequency, intensity, type, time, volume) on hypertension and birth outcomes in pregnant women. STUDY DESIGN: This study is a retrospective, secondary analysis of pooled data from three blinded, prospective, randomized controlled trials. Women at risk of HDP (11 control, 27 exercise) were identified from the population and monitored in supervised exercise sessions throughout pregnancy. Upon delivery, birth measures were obtained. Pearson correlations and stepwise regressions determined associations. Tests for outcomes between exercise types were completed using one-way ANOVA. RESULTS: Women at risk of HDP with higher total exercise volume trended lower systolic blood pressure during pregnancy (P=.07). In at-risk women, total and weekly exercise volume were then associated with gestational age at birth (R=0.42, P=.03; R=0.46, P=.02) and increased birthweight (R=0.43, P=.03). Weekly exercise duration predicted birthweight (P=.02) independent of gestational age at birth. CONCLUSION: The current findings add to a body of literature showing the beneficial influence of exercise during pregnancy on HDP risk, and importantly the effect on exposed offspring. Prenatal exercise improved birth outcomes in women with higher HDP risk in a dose-dependent manner, whereby higher exercise volume and duration are associated with improvements in birth outcomes.