Weight change (kg) per doubling in PFAS plasma concentrations during pregnancy (gestational weight gain) and 1- and 3-years postpartum, stratified by pre-pregnancy body mass index (BMI) category. Part A. shows PFOS and part B. shows PFOA. All estimates were adjusted for age, pre-pregnancy BMI, marital status, race/ethnicity, education, household income, smoking, and parity. One-year postpartum weight retention and 3-year postpartum weight change estimates were IP-weighted to account for differential loss to follow up.