Impact of gestational diabetes mellitus and assisted reproductive technology on maternal and neonatal outcomes in twin pregnancies: A multicentre retrospective study in China

Aims Twin pregnancies are inherently at high risk of maternal and neonatal complications. Assisted reproductive technology (ART) and gestational diabetes mellitus (GDM) are both common in this population, but it remains unclear whether their coexistence is associated with excess risk beyond their individual associations. Methods In this multicentre retrospective cohort of 4522 liveborn twin pregnancies across three hospitals in China, pregnancies were categorized according to mode of conception and GDM status. Generalized linear mixed models were used to estimate adjusted odds ratios (aORs) and 95% confidence intervals (CIs), with hospital included as a random effect. Multiplicative and additive interaction analyses were performed to assess whether the joint associations of ART and GDM with maternal and neonatal outcomes exceeded their individual associations. Results The overall prevalence of GDM was 22.2%, with 30.0% in ART‐conceived women and 14.0% in spontaneously conceived (SC) women. Compared to SC twin pregnancies without GDM, ART‐conceived twin pregnancies with GDM showed significantly increased risks of placental adhesion (aOR: 1.55; 95% CI: 1.03–2.33), caesarean section (aOR: 2.72; 95% CI: 1.21–6.15), preterm birth <37 weeks (aOR: 1.43; 95% CI: 1.15–1.78) and low birth weight (aOR: 1.27; 95% CI: 1.01–1.60). Notably, statistically significant multiplicative (aOR: 1.76; 95% CI: 1.11–2.80) and additive (relative excess risk due to interaction: 0.55; 95% CI: 0.14–0.96) interactions between GDM and ART were observed for preterm birth <34 weeks, whereas no statistically significant interactions were detected for the other examined outcomes. Conclusion Twin pregnancies with both ART conception and GDM had higher risks of several adverse outcomes than spontaneously conceived pregnancies without GDM. However, evidence of statistical interaction between ART and GDM was limited to preterm birth <34 weeks, suggesting that the excess risk associated with their coexistence may be outcome‐specific. These findings may help refine risk stratification and prenatal surveillance in twin pregnancies.