This study was the first to explore the impaction of maternal total sugar, added sugar, free sugar, fructose, and SSB intake on changes in maternal body weight and body composition during and after pregnancy. A total of 863 pregnant women’ data from the APrON study were analyzed through 36 linear regression models. Maternal dietary intakes were measured through web-based 24-hr recall and a sugar database. Maternal dietary intake, weights and fatness were measured at each trimester and 3-month postpartum visit. Both total and free sugar intake was significantly associated with higher gestational weight and fatness gain between the second and third trimester. Maternal added sugar intake was significantly associated with maternal weight gain between the second and third trimester. Maternal calories intake was proposed as a mediator in this relationship. Future studies should further explore if a low sugar dietary intervention could help with maintaining GWG within a healthy range.