The study compares an occurrence rate of congenital malformations in newborn infants of mothers with insulin dependent diabetes (IDDM) and newborns of healthy mothers and mothers with pregnancy diabetes (GDM). This paper evaluates the influence of stage of advancement (a class) of diabetes in the mother and its control during early pregnancy on a rate of congenital malformations in the fetus. We have taken a group of 170 neonates of mothers with IDDM. The control group was 56 newborn infants of mothers with GDM and 26,368 newborn infants of healthy women. We found 11.2% of congenital malformations in newborn infants of mothers with IDDM, compared to 1.8% of ones in the newborn infant population of mothers with GDM and 2.2% in the population of healthy mothers. The occurrence rate of congenital malformations in offspring of diabetic mothers with IDDM was 5-times higher than in the general population of newborn infants of healthy and also mothers with GDM. A risk of major birth defect occurrence in the fetus was directly proportional to the grade of the blood glucose level control in mothers during the I trimester of pregnancy, but the presence of diabetic angiopathy (classes D-H) had a significant influence on the occurrence rate of major birth defects in the fetus only in metabolic imbalance cases.