Association of pre-pregnancy obesity and excessive gestational weight gain with perinatal outcomes among patients with pregestational diabetes

Aims: Pre-pregnancy 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 pre-pregnancy obesity had worse obstetric outcomes. Material and methods: This was a population-based cohort study using data from 2021-2023 National Vitl Statistics System of singleton, non-anomalous, live births at 23w0d to 41w6d with a history of maternal PGDM. Births were divided into 4 groups based on pre-pregnancy body mass index (pBMI) and gestational weight gain (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 as the referent using logistic regression to adjust for confounders. Results: Of the 53,631 births that met inclusion criteria, 6.3%, 15.1%, 21.5%, 57.0% were in groups 1-4, respectively. After adjusting for maternal age, nulliparity, chronic hypertension, and previous preterm birth, compared with group 1, births in groups 2 (aOR1.93, 95%CI 1.77-2.09), 3 (aOR1.63, 95%CI 1.51-1.77), and 4 (aOR2.54, 95%CI 2.36-2.73) had higher odds of composite adverse pregnancy outcomes. Conclusion: Both pre-pregnancy 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 pre-pregnancy weight optimization and gestational weight management to reduce associated risks.