Data on maternal ethnicity, age, educational attainment, regular cigarette smoking, and self-reported pre-pregnancy weight were collected from participants at recruitment. Maternal weights (SECA model 803, SECA Corp., Hamburg, Germany) and height during pregnancy (SECA stadiometer model 213) were measured. Total weight gains were calculated by subtracting self-reported pregnancy weight from the last measured weight before delivery. Pre-pregnancy BMI was calculated as weight(kg)/height2 (m2). Gestational diabetes mellitus (GDM) was defined based on the 1999 World Health Organization (WHO) criteria21 (link),22 (link).