The impact of gestational diabetes mellitus on the development of pregnancy outcomes in twin pregnancies: a retrospective cohort study conducted at a tertiary hospital

Abstract Background: The impact of gestational diabetes mellitus (GDM) on pregnancy outcomes in twin pregnancies has not been fully understood. This study aimed to examine the effects of GDM on the risk of pregnancy outcomes in twin pregnancies and to investigate the relationship between glycemic levels and the risk of preeclampsia (PE) and abnormal fetal growth. Methods: A retrospective cohort study of 736 twin pregnancies was conducted at a tertiary hospital in Hangzhou, China. Propensity score matching and multivariable logistic models were utilized to compare maternal and neonatal outcomes between twin pregnancies with GDM and those without GDM. Multivariable logistic regressions were performed to address the intertwin correlation between glycemic levels and the primary outcomes. Results were reported as odds ratios (ORs) with 95% confidence intervals (CIs). Results: There was no significant difference in the risk of PE between non-GDM and GDM pregnancies (OR, 0.70; 95% CI: 0.38-1.27; P = 0.238). Women without GDM were less likely to require admission to the intensive care unit compared with women with GDM (OR, 0.19; 95% CI: 0.06-0.57; P = 0.003). No significant differences were found in the other maternal and neonatal outcomes between the study groups, including small and large for gestational age. Women with fasting blood glucose levels from 5.1 mmol/L to less than 5.3 mmol/L had a significantly higher risk of PE compared with women without GDM (OR, 2.90; 95% CI: 1.12-7.51; P = 0.028). In subgroups of HbA1c, HbA1c ≥ 5.5% had the highest risk of PE in the second and third trimesters compared with women without GDM (OR, 4.90; 95% CI: 1.00-24.12; P = 0.05). Conclusion: The risk of PE was not increased in twin pregnancies complicated with GDM, but significantly increased in women with an HbA1c ≥5.5%. Twin pregnancies with GDM had a higher risk of admission to the intensive care unit compared with non-GDM twin pregnancies. Strict glycemic control may decrease the risk of PE in twin pregnancies with GDM.