Attenuated Impact of Gestational Diabetes Mellitus (GDM) With Hypertensive Disorders of Pregnancy (HDP) on Adverse Pregnancy Outcomes in Twin Versus Singleton Gestations: A Single-Center Real-World Study.

objectiveGestational diabetes mellitus (GDM) and hypertensive disorders of pregnancy (HDP) are two of the most prevalent pregnancy complications affecting both singleton and twin pregnancies worldwide. This study specifically investigates the combined effect of concurrent GDM and HDP on maternal and perinatal outcomes among twin gestation populations.

methodsThis retrospective single-center study enrolled 132,314 pregnant people who delivered at ≥ 20 weeks of gestation as the eligible study population, including 918 stillbirth cases, 2803 live twin births, and 128,593 live singleton births. All included cases met core inclusion and exclusion criteria. The total population was categorized into four subgroups according to the presence of HDP and/or GDM: non-HDP-GDM, HDP only, GDM only, and concurrent HDP-GDM. The primary analysis focused on comparing perinatal outcomes between twin and singleton pregnancies within each of the four subgroups to evaluate the effect of HDP, GDM, and their co-occurrence on perinatal outcomes across different pregnancy types.

resultsAmong the 132,314 pregnant people included in this study, the stillbirth rate in twin pregnancies was higher than that in singleton pregnancies (1.79% vs. 0.67%, p < 0.001). Distinct differences in maternal and neonatal complication profiles were observed between singleton and twin pregnancies, and this discrepancy persisted across both term and preterm subgroups. The incidence of HDP and GDM in twin pregnancies was 23.0% and 21.0%, respectively. Across all subgroups, twin pregnancies were associated with preterm birth (PTB), cesarean section (CS), and anemia. Interestingly, the number of complications showing comparable occurrence patterns between singleton and twin pregnancies was 3 in the non-HDP-GDM group, 6 in the HDP group, 8 in the GDM group, and 15 in the HDP-GDM group. Notably, the positive association between HDP/GDM and adverse outcomes observed in singleton pregnancies was not equivalently present in twin pregnancies. In singleton pregnancies, the combined effect of HDP and GDM on adverse outcomes could either synergistically amplify or counteract (attenuate) their individual impacts, depending on whether their individual effects were congruent-a pattern with synergistic amplification when individual risks were congruent. In contrast, the combined influence of HDP and GDM showed limited association with adverse outcomes in twin pregnancies.

conclusionsAlthough the individual incidence of HDP and GDM is higher in twin pregnancies, their combined effect on adverse perinatal outcomes is attenuated in twin populations. This retrospective single-center finding offers reference for individualized risk assessment of twin pregnancies.