A total of 1035 births to diabetic mothers were registered in Norway during the 10-year period 1967-1976. Perinatal mortality (from 16 weeks of gestation until 7 days after birth) decreased from 177.4 per 1000 births in 1967-68 to 60.7 in 1975-1976; for the total population the figures were 24.1 and 18.4. During the same period the duration of gestation increased from 35.5 weeks in 1967-1968 to 37.0 weeks in 1975-1976. The numbers of small and large infants decreased: in 1967-1968 53.3% weighed 2500-4000 grams, in 1975-1976 70.7%. Moreover, more births took place in university clinics and regional hospitals, 38.7% in 1967-1968 and 77.1% in 1975-1976. Malformations were 50% more common in children of diabetics. Cardiovascular and nervous system malformations accounted for this increase, being 5 times more frequent than in the general population.