Maternal overweight and obesity and risk of pre-eclampsia in women with type 1 diabetes or type 2 diabetes

Aims/hypothesis Women with type 1 or type 2 diabetes are at increased risk of pre-eclampsia. Overweight and obesity are associated with an increased risk of pre-eclampsia in women without diabetes. The aim of the study was to investigate the impact of maternal overweight and obesity on the risk of pre-eclampsia in women with type 1 diabetes or type 2 diabetes. Methods In a population-based cohort study including singleton births in Sweden, we estimated the risk of pre-eclampsia among women with type 1 diabetes ( n = 7062) and type 2 diabetes ( n = 886), and investigated whether maternal overweight (BMI 25–29.9 kg/m 2 ) and obesity (BMI ≥30.0 kg/m 2 ) modified the risk. Logistic regression analyses were used to estimate crude and adjusted ORs with 95% CIs, using women without diabetes as the reference group ( n = 1,509,525). Results Compared with women without diabetes, the adjusted ORs for pre-eclampsia in women with type 1 and type 2 diabetes were 5.74 (95% CI 5.31, 6.20) and 2.11 (95% CI 1.65, 2.70), respectively. The corresponding risks of pre-eclampsia combined with preterm birth were even higher. Risks of pre-eclampsia increased with maternal overweight (BMI 25–29.9 kg/m 2 ) and obesity (BMI ≥30.0 kg/m 2 ), foremost in women without diabetes, to a lesser extent in women with type 1 diabetes but not in women with type 2 diabetes. Conclusions/interpretation Maternal overweight and obesity increased risks of pre-eclampsia in women with type 1 diabetes but not in women with type 2 diabetes. Even so, considering associations between maternal BMI and overall maternal and offspring risk, all women (with and without diabetes) should aim for a normal weight before pregnancy.