['A nationwide recommendation to standardize the care of diabetic pregnancies in different hospitals was given in Finland in 1993. The Medical Birth Register (MBR) was used to investigate whether these recommendations have been accepted and how they have affected the outcome of newborns.', 'Data on 1442 singleton pregnancies complicated by insulin-treated diabetes in 1991-1995 were obtained from the MBR.', 'The incidence of insulin treatment during pregnancy was 4.5 per 1000 births. Sixty-six per cent (n = 954) of all women had Type 1 diabetes. During the study period, the number of deliveries managed in tertiary centres decreased from 59% to 47% (95% confidence interval [CI] 39-58%) and care was more often carried out on an out-patient basis. The perinatal mortality rate (>or= 28 weeks of gestation) declined from 19.3 to 8.2/1000, being 12.6/1000 in the whole diabetic population and 5.5/1000 in the general population (95% CI 3.4-8.8/1000). The risk was especially increased in insulin-treated gestational diabetic (GDM) pregnancies (14.3/1000). The proportion of macrosomic newborns (31.7%) in diabetic women was significantly higher than among the general population (3.2%) (95% CI 27.0-33.9%).'] Does a uniform regimen enable decentralized care of diabetic pregnancies?