Prevalence and recurrence rate of gestational diabetes: A nationwide cohort study

Objective: To determine the prevalence and recurrence of gestational diabetes mellitus (GDM) in Danish live births from 2004 to 2017, to support and expand existing knowledge on prevalence, recurrence and risk factors. Methods: This registry-based cohort study included all women giving birth in Denmark during the study period. Data from the Danish Medical Birth Registry identified 784,545 singleton deliveries, of which 22,309 (19,559 women) were complicated by GDM. Maternal age, pre-pregnancy BMI, smoking in pregnancy and parity were analyzed as risk factors. Proportions, including recurrence risk, were calculated. Results: The prevalence of GDM increased from 1.8% in 2004 to 4.2% in 2017. Overweight women (BMI 25–29.9) had a threefold increased risk of GDM; OR 3.26 (95% CI 3.15–3.38); while obese women (BMI ≥ 30) had an almost eightfold increased risk; OR 7.78 (95% CI (7.53–8.04). Increasing parity was associated with reduced risk of GDM, though not monotonically. Smoking was not associated with GDM; OR 0.99 (95% CI 0.95–1.04). The overall recurrence risk was 48.5% (95% CI 47.1–49.8); lower in women first diagnosed in their second pregnancy (43.7% (95% CI 40.0–47.4)) than in those diagnosed in their first pregnancy (49.2% (95% CI 47.7–50.6)). Conclusions: Despite an increasing prevalence of GDM, the recurrence rate remained stable. Higher BMI and maternal age were key factors for GDM, whereas smoking and parity were not consistently associated with risk. This knowledge on recurrent GDM and risk factors for recurrent GDM may contribute to optimization of future treatment strategies.