Congenital malformations: the possible role of diabetes care outside pregnancy.

A consecutive and prospective series comprising 949 newborn infants of diabetic mothers treated during pregnancy and delivery in the period 1966--1977 has been analysed. The malformation rate was 8.2%. As compared to infants of mothers (White classes B-F alone) controlled outside pregnancy elsewhere, the rate of malformations was significantly reduced (from 14.1 to 7.4%) in fants whose mothers attended two hospitals specializing in the treatment and ambulatory control of diabetics. For diabetics not controlled at a diabetic centre outside pregnancy the malformation rate was 9% in classes B + C and 19.4% in classes D + F, compared to 6.2 and 8.5%, respectively, for those who were controlled. The rates of malformation (total as well as severe alone) were significantly reduced in infants of White's classes D + F, and insignificantly reduced in classes B + C (in class A no comparison could be made). The findings indicate that poor diabetic control outside pregnancy is teratogenic, although the 'disastrous malformation factor' of diabetes appears not to be totally dependent on the degree of compensation of the disbetic metabolism, as measured by the variables usually applied.