Association of trimester-specific gestational weight gain with child BMI by maternal BMI categories in community-based healthcare organizations

Abstract Background/Objectives Information is lacking about how trimester-specific gestational weight gain (GWG) is associated with childhood body mass index (BMI) across maternal BMI categories. Subjects/Methods We examined the association between GWG and child BMI in patients receiving care from a national network of community health care organizations. We stratified by pre-pregnancy BMI ( n = 5721 normal weight; 5667 overweight; 3213 obesity class I; 1344 class II; 692 class III). Child BMI z -score and overweight and obesity status at age 5 were modeled as a function of total GWG and GWG rate in each trimester, controlling for GWG rate in previous trimester(s) and maternal characteristics, using linear or modified Poisson regression. Results Higher total GWG during pregnancy was positively associated with child BMI at 5 years of age in a linear, dose-dependent manner. When stratified by BMI, each 1 kg/week greater weight gain in the first trimester was associated with a 0.25–0.45 increase in child BMI z -score, depending on BMI class. Each 1 kg/week weight gain in the 2 nd trimester was associated with a 0.28 to 0.52 increase in child BMI z -score, although the associations were not significant in class III obesity. Associations between GWG in the third trimester and child BMI z -score were weak (−0.07 to 0.21 increase in BMI z -score per kg/week increase in maternal weight) and generally not significant. Conclusion Among a diverse and systemically underserved pregnant population, GWG in the 1 st and 2 nd trimesters are most strongly associated with child BMI at age 5. Early pregnancy and mid-pregnancy may be key times to intervene to prevent overweight and obesity in offspring.