Association of Prepregnancy Obesity and Excessive Gestational Weight Gain with Perinatal Outcomes among Patients with Pregestational Diabetes

Prepregnancy obesity, excessive gestational weight gain (GWG), and pregestational diabetes (PGDM) are individually associated with adverse maternal and neonatal outcomes. However, little is known about the intersection of these comorbidities. This study aimed to determine if patients with PGDM and excessive GWG or prepregnancy obesity had worse obstetric outcomes.This was a population-based cohort study using data from the 2021 to 2023 National Vital Statistics System of singleton, nonanomalous, live births at 23^0/7 to 41^6/7 weeks with a history of maternal PGDM. Births were divided into four groups based on prepregnancy body mass index (pBMI) and GWG: (1) normal pBMI and GWG, (2) normal pBMI and excessive GWG; (3) obese pBMI and normal GWG, and (4) obese pBMI and excessive GWG. The primary outcome, a composite of maternal and neonatal adverse outcomes, was compared with group 1 (births from parents with normal pBMI and GWG) as the referent using logistic regression to adjust for confounders.Of the 53,631 births that met the inclusion criteria, 6.3, 15.1, 21.5, 57.0% were in groups 1 to 4, respectively. After adjusting for maternal age, nulliparity, chronic hypertension, and previous preterm birth, compared with group 1 (normal pBMI-normal GWG), births in groups 2 ( normal pBMI-excess GWG; adjusted odds ratio [aOR]: 1.93, 95% confidence interval [CI]: 1.77-2.09), 3 ( obese pBMI-normal GWG; aOR: 1.63, 95% CI: 1.51-1.77), and 4 ( obese pBMI-excess GWG aOR: 2.54, 95% CI: 2.36-2.73) had higher odds of composite adverse pregnancy outcomes.Both prepregnancy obesity and excessive GWG are associated with adverse perinatal outcomes in pregnancies complicated by PGDM. Excessive GWG was a stronger driver of these outcomes. These findings highlight the importance of prepregnancy weight optimization and gestational weight management to reduce associated risks. · Prepregnancy obesity and excessive GWG are associated with adverse perinatal outcomes in pregnancies complicated by PGDM.. · Excessive GWG and obese BMI had the worst perinatal outcomes.. · Excessive GWG was a stronger predictor of adverse perinatal outcomes than obese prepregnancy BMI.. · Class III prepregnancy obesity (BMI ≥ 40) with normal GWG had similar rates of composite adverse pregnancy outcomes as those with normal BMI and excessive GWG..