Greater Early and Mid-Pregnancy Gestational Weight Gains are Associated with Excess Adiposity in Mid-Childhood

Objective: It is unclear how specific periods of gestational weight gain (GWG) during pregnancy relate to childhood adiposity. The goal of this study was to assess the differential impact of GWG timing on childhood body composition. Methods: In 979 mother-child pairs from the pre-birth Project Viva cohort, trimester-specific GWG was calculated using clinically recorded weights. Outcomes included body mass index (BMI) z-score, dual X-ray absorptiometry fat mass index (kg/m(2)), and fat-free mass index (kg/m(2)) in mid-childhood. Linear regression models were used to assess associations of each trimester's GWG (per 0.2 kg/week) with childhood outcomes, adjusted for maternal prepregnancy BMI, sociodemographic variables, lifestyle, and GWG in prior trimester(s). Results: Mean (SD) first trimester GWG was 0.22 (0.22) kg/week, second trimester 0.49 (0.18) kg/week, and third trimester 0.47 (0.20) kg/week. Faster first trimester GWG was associated with higher BMI z-score (0.06 units [95% CI: 0.01-0.12] per 0.2 kg/week) and with higher adiposity according to all indices; associations were strongest in women with prepregnancy BMI >30 kg/m(2). Faster second trimester GWG was associated with higher BMI z-score (0.11 [0.04-0.18]), fat mass (fat mass index = 0.16 [0.02-0.31] kg/m(2)), and lean mass (fat-free mass index = 0.11 [0.01-0.22] kg/m(2)). Third trimester GWG was not associated with childhood adiposity. Conclusions: These results reinforce the importance of addressing appropriate GWG in early pregnancy.