A national population-based pregnancy cohort, compiled at 231 maternity units in the United Kingdom, enrolled 2359 diabetic women in a 12-month period. Type 1 diabetes was diagnosed in 1707 enrollees and type 2 diabetes in 652. Compared to women with type 1 diabetes, those with type 2 diabetes were more likely to come from a black, Asian, or other ethnic minority group, and also likelier to be from a deprived area. In addition, these women were older at the time diabetes was diagnosed and also at the time of delivery. They were less likely than women with type 1 diabetes to be primigravidas. Just over one-third of the 1606 women studied by 13 weeks' gestation had good glycemic control.
Adjusting for maternal age, stillbirths were 4.7 times more frequent in diabetic women than in the general maternity population. Rates of perinatal and neonatal mortality were 3.8-fold and 2.6-fold greater, respectively, in cases of diabetes. Perinatal mortality rates were comparable in cases of type 1 and type 2 diabetes. The prevalence of major congenital anomalies in women with diabetes was more than double that expected. Much of the difference was accounted for by nervous system anomalies – particularly neural tube defects – and congenital heart disorders. Nearly two-thirds of infants with anomalies were diagnosed before birth. Congenital heart disease was diagnosed antenatally in 55% of offspring, and other anomalies in approximately 72%.
Compared to the general maternity population, infants of women who have type 1 or type 2 diabetes are at increased risk of dying perinatally and of having congenital anomalies. The number of pregnant women with diabetes is expected to increase. There is evidence that good glycemic control at the time of conception and in early pregnancy can reduce adverse outcomes, but a majority of diabetic women fail to achieve such control.