School marks for Swedish children whose mothers had diabetes during pregnancy: a population-based study

To study, at a population level, school performance when leaving compulsory school of Swedish children whose mothers had diabetes during pregnancy compared with a reference population.

We linked the Swedish Medical Birth Register with the Swedish School Mark Register, which contains school marks for all children in Sweden when leaving compulsory school. A total of 6,397 children were identified whose mothers had a diagnosis of diabetes during pregnancy in the years 1973 to 1986. Data on these children were compared with 1,300,683 children whose mothers had no diagnosis of diabetes during pregnancy. Risks were estimated as odd ratios (ORs) after adjustment for year of birth, maternal age, parity and educational level of the mother.

The children's average numerical school marks (for children leaving school between 1988 and 1997) were statistically significantly lower among children born to mothers with diabetes in pregnancy compared with reference children (3.13 +/- 0.01 vs 3.23, p < 0.001). The effect was similar among boys and girls. There was also an effect of maternal diabetes during pregnancy on the risk of the child not completing compulsory school (OR 1.25; 95% CI 1.10-1.43, and after exclusion of infants with certain perinatal characteristics an OR of 1.25; 95% CI 1.02-1.53). When sports and the core subjects mathematics, English and Swedish were studied, there were increased risks of having scores below pass level and decreased probabilities of having scores above pass level for children of mothers with diabetes during pregnancy.

Children of mothers with diabetes during pregnancy performed slightly but significantly less well than reference children when leaving compulsory school at about 16 years old; this was also seen after adjustment for some putative perinatal and social confounders.