Congenital anomalies and first life year surveillance in Type 1 diabetic births

To evaluate the rate of congenital anomalies (CA) and the reasons for mortality from 22 weeks of gestation until 1 year of age in births by Type 1 diabetic mothers.

Population-based cohort study using combined data from four national health registers in Finland during 1991-1995, including 954 singleton pregnancies complicated by Type 1 diabetes.

Sixty births (629/10 000) involved registered major CA, of which 68% (n = 41) were isolated and 22% (n = 13) multiple anomalies, and in six cases, a syndrome was diagnosed (10%). After the exclusion of syndromes, the total number of anomalies was 73. Of the malformed infants, 63% were boys. The total rate of deaths among births until 1 year of age was higher in diabetic than in non-diabetic mothers (19.9/1000 vs. 8.1/1000): especially the rates of stillborns (odds ratio 2.4; 95% confidence interval 1.2-4.7) and post-neonatal deaths (3.8; 1.6-9.2) were higher. Of perinatal mortality (PNM) from the 22nd gestational week to the age of 7 days (13.6/1000), 23% were due to CA, 23% to prematurity, and the rest were intrauterine, mostly unexplained, deaths. Respiratory distress syndrome was the main cause of death among infants.

The rate of CAs in Type 1 diabetic pregnancies is still high, but their proportion as a cause of PNM has decreased. Though PNM rate was low, post-neonatal mortality was significantly increased, reflecting the shift of deaths from the perinatal period to a later age.