Significant decrease in congenital malformations in newborn infants of an unselected population of diabetic women

In an unselected and consecutive series of 1858 newborn infants of diabetic mothers, born in the Rigshospital, Copenhagen, in the period 1967 to 1986, congenital malformations were studied. The malformation rate in White Classes B to F was remarkably constant from 1967 to 1981, but a significant decrease in major congenital malformations was found in the period 1982 to 1986 versus 1977 to 1981 (2.7% vs. 7.4%, p less than 0.05). This decrease was mainly due to a fourfold decline in major congenital malformations in White Classes D and F (p less than 0.01), and consequently a correlation between the severity of maternal diabetes and the frequency of congenital malformations was no longer present. In the offspring of a control group of 1715 nondiabetic women, major congenital malformations were found in 1.7% (p greater than 0.05). Seventy-five percent of the diabetic pregnancies were planned, and in these pregnancies only 1% of the infants had major congenital malformations. The frequency of fatal malformations in White Classes B to F was still significantly higher than in the control group (p less than 0.001).