Do Physical Activity Patterns Across the Lifecourse Impact Birth Outcomes?

The significant impact of physical activity during, or immediately prior to pregnancy on a range of pregnancy and birth outcomes has been established. However, lifecourse theory posits that the antecedents of poor outcomes occur across a larger trajectory of time. The objective of this study was to examine whether physical activity patterns over the lifecourse impact birth outcomes. The sample (n = 1,713) was derived from Waves I, III, and IV of the National Longitudinal Study of Adolescent Health and limited to women who had their first, singleton live birth between Waves III and IV; respondents who had missing data were excluded. Outcome variables included preterm birth (<37 weeks) and low birth weight (<5.5 pounds). Physical activity was categorized as follows: long-term physically active (active at Waves I and III); short-term physically active (active at only Wave I or III); and not physically active (not active at Waves I and III). Survey-weighted logistic regression controlled for socio-demographic and established predictors of poor birth outcomes. Women categorized as long-term physically active had lower rates of preterm births (12.2 vs. 18.7 %) and low birth weight (9.1 vs. 11.1 %) compared to women categorized as not physically active. However, when controlling for covariates, adjusted analysis revealed that physical activity consistency only predicted preterm birth (aOR = 0.55, 95 % CI = 0.33-0.91). Findings suggest that physical activity patterns across the lifecourse may decrease risk of preterm birth. Implications include efforts supporting patterns of physical activity over longer periods of time prior to pregnancy.