Impact of Physical Activity Consistency across the Lifecourse on Birth Outcomes

Background: The importance of lifelong physical activity (PA) on health is well documented. While previous research has examined the impact of PA during pregnancy, (e.g., decrease risk of gestational diabetes, preterm birth, post-partum depression), the effects of pre-gravid PA on pregnancy/birth outcomes remains understudied. The purpose of this study was to examine whether women’s consistent PA patterns over their lifespan impacts birth outcomes.

Methods: Data from Add Health were limited to women with a singleton live birth between Waves III and IV who were not missing data for key variables (n=1,693). Outcome variables: preterm birth (<37 weeks) and low birthweight (LBW; <5.5 pounds). The primary predictor was PA consistency measured at Waves I and III. Those with ≥ 5 instances of moderate-vigorous PA a week were classified as physically “active.” PA consistency was trichotomized as (1) consistently active, (2) not consistently active, or (3) consistently not active. Survey-weighted logistic regression models were estimated.

Results: When adjusting for socio-demographic characteristics (e.g., age, race) and predictors of poor birth outcomes (e.g., smoking, drinking), there was no association between PA consistency and LBW; however, when adjusting for the same factors, women who reported consistent PA were significantly less likely to report a preterm birth compared to women who were consistently not active (aOR: 0.58, 95% CI: 0.36 – 0.94).

Conclusion: Findings suggest that consistent PA over the lifecourse among women could decrease preterm birth, a leading cause of infant mortality. Future research is needed to confirm and elucidate potential mechanisms of this association.