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.
Keywords: BMI; Diabetes type 1; Diabetes type 2; Moderate pre-eclampsia; Obesity; Overweight; Pre-eclampsia; Risk of pre-eclampsia; Severe pre-eclampsia.