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

We evaluated the association between gestational weight gain (GWG) and preeclampsia (PE) in twin pregnancies and explored potential non-linear patterns in continuous GWG.

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.

PE occurred in 10.6% of women. Compared with excessive GWG, both inadequate (aOR 0.22, 95% CI 0.07-0.66; p = 0.007) and adequate GWG (aOR 0.39, 95% CI 0.16-0.98; p = 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.

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.