Association between gestational weight gain and pregnancy outcomes, neonatal birth weight, and maternal postpartum glucose tolerance in Japanese gestational diabetes mellitus patients: comparison of old and new gestational weight gain standards

In Japan, the guidelines for gestational weight gain (GWG) were revised in 2021. Under the new guidelines, pregnant women are recommended to increase their GWG. The aim of this study was to compare the incidence of adverse pregnancy outcomes (APOs), large for gestational age (LGA), and postpartum glucose tolerance in gestational diabetes mellitus (GDM) patients before and after the revised GWG standards. This retrospective cohort study enrolled 1,021 GDM patients who underwent prenatal glycemic control and a postpartum 75-g oral glucose tolerance test. The endpoint was the incidence of APOs, LGA, and postpartum impaired glucose tolerance (IGT) and diabetes mellitus (DM). There was no significant difference in the incidence of APOs and postpartum IGT and DM in GDM patients before and after the revised GWG standards. On the other hand, when the new GWG standards were applied to GDM patients, the incidence of LGA increased (adjusted odds ratio [aOR]; 1.764, 95% confidence interval [CI]; 1.180-2.637). In particular, when classified by prepregnancy body mass index, the incidence of LGA increased in the obese group (aOR; 5.944, 95% CI; 1.847-19.129). Future prospective cohort studies are needed to verify the efficacy and safety of appropriate GWG in Japanese GDM patients.