16 Jul Incidence and Risk Factors for Gestational Diabetes Mellitus in Twins Versus Singletons Pregnancies
Objective: It remains a matter of debate as to whether women with twins are at increased risk of gestational diabetes mellitus (GDM). We aimed to compare the incidence and risk factors for GDM between women with twin and singleton pregnancies using a large population-based cohort. Methods: Retrospective study of all women who had a twin or singleton birth in Ontario between 2012-2016. Data were obtained from the Better Outcomes Registry & Network (BORN) Ontario, a province-wide registry of all births in Ontario, Canada. Risk ratios (RR) and 95% CIs for GDM (stratified by type of treatment) were adjusted for relevant confounding variables. Multivariable Poisson regression analysis was used to identify risk factors for GDM in twin and singleton gestations. Results: Of a total of 561,798 women who gave birth in Ontario during the study period, 270,843 met inclusion criteria. Of them 266,942 (98.6%) and 3,901 (1.4%) had a singleton and a twin pregnancy, respectively. Women with twins had a significantly higher risk for overall GDM (aRR=1.13, 95%-CI 1.01-1.28) and diet-treated GDM (aRR=1.20, 95%-CI 1.01-1.42) while the association with insulin-treated GDM was not significant (aRR=1.07, 95%-CI 0.89-1.28). Maternal age ≥35 years, non-Caucasian ethnicity and BMI >30kg/m2 were independent risk factors for GDM among women with both twins and singletons, and the magnitude of the association of these factors with GDM was similar for both groups. Conclusions: Women with twins are at increased risk of GDM, mainly due to a higher rate of diet-treated GDM. Still, despite the higher baseline risk of GDM in women with twins, the effect of known risk factors for GDM in twin pregnancies is similar to that observed in singletons.