Association between pre-pregnancy body mass index and gestational weight gain and perinatal outcomes in pregnant women diagnosed with gestational diabetes mellitus: The Japan Environment and Children's Study.

AIMS/INTRODUCTION We investigated the association between gestational diabetes mellitus (GDM) and perinatal outcomes stratified by pre-pregnancy body mass index (BMI) and/or gestational weight gain (GWG). MATERIALS AND METHODS Data from the national birth cohort in the Japan Environment and Children's Study from 2011 to 2014 (n = 85,228) were used. Japan uses GDM guidelines of the International Association of Diabetes and Pregnancy Study Groups. The odds ratios (ORs) of perinatal outcomes were compared between women with and those without GDM. RESULTS The OR (95% confidence interval [CI]) of having an SGA infant in the GDM group with a pre-pregnancy BMI of ≥25.0 kg/m2 and insufficient GWG ( 7.25 kg) was 2.04 (1.56-2.67). The OR of hypertensive disorders of pregnancy (HDP) was higher in women with a BMI ≥18.5 kg/m2 in the GDM group than in the non-GDM group. CONCLUSIONS LGA and HDP were associated with pre-pregnancy BMI and GWG in either normal weight or overweight/obese women, and the relationship was strengthened when GDM was present. Women with GDM and a BMI of ≥25.0 kg/m2 are at risk of having SGA and LGA infants depending on GWG.