Gestational weight gain and preeclampsia in twin pregnancies: a retrospective cohort study

OBJECTIVE: We evaluated the association between gestational weight gain (GWG) and preeclampsia (PE) in twin pregnancies and explored potential non-linear patterns in continuous GWG. METHODS: In this retrospective cohort study, 331 women with twin pregnancies who delivered at a tertiary-level maternal hospital in Beijing, China, between January 2021 and December 2024 were included. Total GWG was calculated as the difference between weight at delivery admission and pre-pregnancy weight, and categorized according to the 2009 Institute of Medicine (IOM) recommendations. GWG was also analyzed as a continuous variable. The primary outcome was PE; secondary outcomes were gestational diabetes mellitus (GDM), postpartum hemorrhage (PPH), and premature rupture of membranes (PROM). Multivariable logistic regression models were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs). Non-linear associations between continuous GWG and PE were assessed using restricted cubic splines. Multicollinearity among covariates was assessed before model fitting, and no evidence of substantial collinearity was identified. RESULTS: = 0.04) were associated with lower risks of PE. Spline analyses indicated a non-linear relationship between continuous GWG and PE risk, with the lowest risk observed at moderate GWG levels. GWG categories were not significantly associated with GDM, PPH, or PROM. CONCLUSIONS: Moderate GWG was associated with the lowest risk of PE in twin pregnancies, whereas excessive GWG increased risk. These findings suggest that moderate GWG may be associated with a lower risk of PE in twin pregnancies. Further prospective studies are needed to clarify temporality and optimal GWG ranges in twin gestations.