Maternal healthy lifestyle during early pregnancy and offspring birthweight: differences by offspring sex.

PURPOSE: Individual maternal lifestyle factors during pregnancy have been associated with offspring birthweight; however, associations of combined lifestyle factors with birthweight and potential differences by offspring sex have not been examined.

MATERIALS AND METHODS: Participants (N = 2924) were identified from a pregnancy cohort in Washington state. Lifestyle factors during early pregnancy were dichotomized based on Alternate Healthy Eating Index score ≥62, leisure time physical activity (LTPA) ≥ 150 min/week, not smoking during pregnancy and Perceived Stress Scale score ≤3, then combined into a lifestyle score (0-4). Regression models were run overall and stratified by offspring sex, prepregnancy overweight/obese (BMI ≥25 kg/m2 ) and prepregnancy LTPA.

RESULTS: Overall, 20% of participants had healthy diet, 95% were nonsmokers, 55% had low stress levels, and 66% were physically active. Lifestyle score was not associated with birthweight (β = 3.3 g; 95% CI: -14.5, 21.0); however, associations differed by offspring sex (p = .009). For each unit increase in lifestyle score, there was a suggested 22.4 g higher birthweight (95% CI: -2.7, 47.6) among males and 14.6 g lower birthweight (95% CI: -39.9, 10.7) among females. Prepregnancy BMI and LTPA did not modify associations.

CONCLUSIONS: Healthy lifestyle score in early pregnancy may be associated with greater birthweight among male offspring, but lower birthweight among female offspring.