The association between first trimester physical activity levels and perinatal outcomes

Objective: Physical activity in pregnancy decreases the risk of adverse maternal and neonatal outcomes. This study evaluates the association between first trimester physical activity, assessed by Kaiser Physical Activity Survey (KPAS) scores, and adverse perinatal outcomes. Study design: This is a secondary analysis of a prospective cohort study in which patients were administered the KPAS in each trimester. The primary outcomes were birthweight, large for gestational age (LGA), and small for gestational age (SGA) neonates. Secondary outcomes were composite neonatal morbidity (neonatal acidemia with pH<7.1, hypoxic ischemic encephalopathy, mechanical ventilation, hypoglycemia, and suspected sepsis), gestational diabetes, gestational hypertension, preeclampsia, inadequate and excess gestational weight gain. Outcomes were compared between patients with and without high physical activity levels during early pregnancy, defined as 1st trimester KPAS scores ≥75th percentile and <75th percentile, respectively. Multivariable logistic regression was used to adjust for confounders. Results: A total of 1,045 patients with a complete 1st trimester KPAS were included in this analysis and 262 patients were in the top quartile of physical activity levels in early pregnancy. Higher physical activity levels in the 1st trimester were associated with numerically but not clinically significantly higher birthweights (3191.3±696.1 vs 3076.3±719.8 g, P=.03) with no difference in rates of SGA (10.3% vs 13.3%, P=.25, aRR 0.79; 95% CI 0.52, 1.16) or LGA neonates (8.0% vs 7.3%, P=.80, aRR 1.14; 95% CI 0.68, 1.81). Higher physical activity levels were associated with decreased rates of composite neonatal morbidity (8.4% vs 15%, P<.01, aRR 0.59; 95% CI 0.37, 0.89) and gestational hypertension (6.5% vs 12.9%, P<.01, aRR 0.56; 95% CI 0.33, 0.89). Gestational weight gain and the incidence of gestational diabetes and preeclampsia were similar between groups. Conclusion: Higher levels of physical activity in the first trimester are associated with higher birth weights and lower rates of composite neonatal morbidity and gestational hypertension.