Relations of early pregnancy BMI, gestational weight gain and 1‐year weight retention to maternal body weight outcomes between 1 and 2 years postpartum

This study examined relations between early pregnancy BMI (kg/m 2 ), gestational weight gain (GWG) and maternal body weight outcomes between 1 and 2 years postpartum (1‐2YPP) in a sample of 413 women in upstate New York who participated in a prospective cohort study that followed women from early pregnancy to 2YPP. Most women had BMI < 25 in early pregnancy (N = 214, 52%), and 166 women (40%) exceeded the IOM guidelines for GWG. Over half of the women gained weight between 1‐2YPP (212, 51%). Over half (225, 55%) of the women reached early pregnancy weight or below by 2YPP (EPW2Y). Sixty‐one (15%) women had major weight retention at both 1 and 2YPP, while 35 (9%) moved to a higher risk BMI category by 2YPP (HBMI2Y). Early pregnancy BMI (p < 0.05) and GWG (p < 0.01) were positively related to major weight retention at 1 and 2YPP, but not to weight change between 1‐2YPP. GWG was inversely related to EPW2Y (p < 0.01) and positively to HBMI2Y (p < 0.05) in models unadjusted for 1Y weight retention (1YWR), but not after adjustment for 1YWR. 1YWR was inversely related to weight change 1‐2YPP (p < 0.001), weight gain 1‐2YPP (p < 0.01) and EPW2Y (p < 0.001), and positively to HBMI2Y (p < 0.001). Weight gain between 1 and 2YPP was common in this sample, and should be accounted for in order to prevent misclassification of postpartum weight gain as retention of GWG.