Ludvigsson JF, et al. - Using the Swedish national diabetes register, this population based historical cohort study was conducted to investigate the relationship between maternal type 1 diabetes and the risk of major birth defects. Study participants were 2,458 singleton liveborn infants of mothers with type 1 diabetes and 1,159,865 infants of mothers without diabetes. Researchers reported that increasingly worse glycemic control in the three months before or after estimated conception was linked with a progressively increased risk of major cardiac defects among liveborn infants of mothers with type 1 diabetes. The risk of major cardiac defects was more than twice that of infants of mothers without diabetes, even with glycated hemoglobin within target levels recommended by guidelines (< 6.5%). Although the study had limited statistical power for this outcome and was based on live births only, the risk of major non-cardiac defects was not statistically significantly increased at any of the four levels of glycated hemoglobin examined.