Interactive effects of prepregnancy overweight and gestational diabetes on macrosomia and large for gestational age: A population-based prospective cohort in Tianjin, China.

•Pregnancy overweight was associated with a 2.3-fold risk of macrosomia and large-for-gestational age (LGA) infants.•Gestational diabetes (GDM) and prepregnancy overweight had a synergistic effect on the risk of macrosomia and LGA.•Our findings highlight the importance to maintain normal body weight before pregnancy for perinatal health.