Pregnancy in diabetic patients was uncommon before 1960 in Japan. It has increased recently and there has been a 3-fold increase since 1971. Only 26% of the cases of diabetic pregnancy had IDDM; the rest of cases had NIDDM. The perinatal mortality of infants decreased from 10.8% in 1971-1975 to 1.1% in 1986-1990, but the incidence of congenital malformations remained at 5.7-8.2% during this period. From 1988 to 1992, we experienced 207 deliveries at the Diabetes Center, Tokyo Women's Medical College. The ratio of IDDM to NIDDM of the mothers was 33:67. The onset of diabetes of pregnant women occurred earlier and the duration of diabetes was longer in IDDM than in NIDDM (mean onset, 17.8 vs. 26.0 years; mean duration, 11.5 vs. 5.6 years). The prevalence of maternal complications was similar between the IDDM and NIDDM mothers. Proliferative retinopathy in NIDDM was often detected for the first time during pregnancy. Major congenital malformations were found in none of the infants of IDDM mothers but in 5.8% of the infants of NIDDM mothers. This is probably related to the poor management of diabetes in NIDDM before pregnancy.