Long-term risk for maternal cardiovascular morbidities in twin pregnancies complicated with gestational diabetes mellitus–a retrospective cohort study^†

Background: Gestational diabetes mellitus (GDM) results in an increased risk for maternal and neonatal complications in singletons. In twin pregnancies, however, scarce data exist regarding its implications. Objective: To investigate whether a diagnosis of GDM in twin gestation poses a risk for subsequent maternal long-term cardiovascular morbidity. Study design: A population-based cohort study was conducted, comparing the incidence of cardiovascular morbidity within a group of women with and without a diagnosis of GDM who delivered twins in a tertiary medical center, between the years 1991 and 2014. Mothers with pregestational diabetes mellitus, triplet or higher-order multiples, patients lacking prenatal care, patients with known cardiovascular morbidities prior to or during the current pregnancy and fetal malformations or/and chromosomal abnormalities were excluded. Kaplan–Meier’s survival curve was used to estimate the cumulative incidence of cardiovascular-related hospitalizations, and a Cox proportional hazards model was used to estimate the adjusted HRs for cardiovascular morbidity. Results: Of 4256 twin deliveries that met the inclusion criteria, 336 (7.9%) occurred in patients that were diagnosed with GDM. During a follow-up period of more than 10 years, with a median of 3431 (0–9172) days in total, patients with GDM had higher rates of simple cardiovascular events as compared to women without diagnosis of GDM (incidence = 7, 2.1%. OR = 2.7, 95% confidence interval (CI) 1.17–6.12, p =.03). Total cardiovascular hospitalizations were comparable between the groups. There was no difference between the two groups in the rate of complex cardiovascular events, noninvasive or invasive cardiac diagnostic procedures. In a Cox proportional hazards model, which is adjusted for maternal age, ethnicity, hypertensive disorders, and fertility treatments, GDM in twin pregnancies was not found to be associated with long-term cardiovascular morbidity (adjusted HR 1.41, 95% CI 0.77–2.58, p =.26). Conclusions: While GDM during twin pregnancy might be associated with long-term maternal simple cardiovascular events, the complex, as well as the total morbidities, are comparable to patients without GDM.