Objective: The aim of this study was to compare pregnancy outcomes in type 1 diabetic pregnancies with the background population.

Research design and methods: This nationwide prospective multicenter study took place in eight Danish centers treating pregnant women with type 1 diabetes during 1993-1999. A total of 990 women with 1,218 pregnancies and delivery after 24 weeks (n=1,215) or early termination due to severe congenital malformations (n=3) were included. Data were collected prospectively by one to three caregivers in each center and reported to a central registry.

Results: The perinatal mortality rate was 3.1% in type 1 diabetic pregnancies compared with 0.75% in the background population (RR 4.1 [95% CI 2.9-5.6]), and the stillbirth rate was 2.1% compared with 0.45 (4.7 [3.2-7.0]). The congenital malformation rate was 5.0% in the study population and 2.8% (1.7 [1.3-2.2]) in the background population. Six of the perinatal deaths (16%) were related to congenital malformations. Only 34% of women performed daily home monitoring of blood glucose at conception, and 58% received preconceptional guidance. Pregnancies with serious adverse outcomes (perinatal death and/or congenital malformations) were characterized by higher HbA1c values before and during pregnancy and a lesser degree of maternal self-care and preconceptional guidance. Women who performed daily self-monitoring of blood glucose at any time during pregnancy had lower HbA1c values than women who did not measure their daily profile. Likewise, daily self-monitoring was associated with a reduction in serious adverse outcomes. The caesarean section rate was 55.9 and 12.6%, respectively, and the risk of preterm delivery was 41.7 and 6.0%, respectively.

Conclusions: Type 1 diabetic pregnancies are still complicated by considerably higher rates of severe perinatal complications compared with the background population, and women with poor self-care are at the highest risk. Adequate glycemic control using daily glucose monitoring before and during pregnancy is a crucial step toward reaching the goals of the St. Vincent declaration.