A recent study analyzing data from more than 2.6 million live births found that infants born by elective cesarean section were at significantly increased risk for type 1 diabetes, and that this increased risk appeared to be associated with family history. Previous studies have suggested that mode of delivery may be associated with type 1 diabetes, and this article, published online in the journal Pediatrics on August 04, 2014, appears to confirm this view. Prof. Khashan and colleagues analyzed data on 263,80883 singleton live births born in Sweden between 1982 and 2009 and found that infants born by elective cesarean (excluding emergency cesarean) had a 15% increased risk of developing type 1 diabetes by age 15 years. In addition, Professor Khashan et al. found a similar association between instrument-assisted vaginal delivery (excluding unassisted vaginal delivery) and diabetes. However, when the researchers performed a regression analysis using the subjects’ siblings as controls, the effect of cesarean delivery and instrument-assisted vaginal delivery on type 1 diabetes was no longer statistically significant. In other words, while this study found that mode of delivery was strongly associated with type 1 diabetes, the mode of birth may not explain the correlation. In the article, the authors write, “The sibling control group analysis suggests that this correlation is not causal and could be explained by family history, environmental factors, or genetic factors.” Also, the authors note that the results of this study have important implications for how women are advised to choose their mode of delivery.” The Swedish medical registry system assigns a unique identifier to each patient born in this country, and using this identifier allows for a seamless connection to other medical and demographic databases. The researchers took advantage of Sweden’s unparalleled data registry system to extract data and statistically analyze that data in two steps. The first step was to exclude potential confounders, including the age of the child, year of birth, gestational age, and the presence or absence of maternal diabetes before pregnancy. Other confounding variables that had little effect on the results could be removed from subsequent regression models, including birth order, maternal age, body mass index, place of birth, educational attainment, gestational diabetes, and preeclampsia. The authors noted that although the association between mode of delivery and diabetes risk was independent of multiple maternal, gestational, and obstetric factors, there were no significant differences in the risk of type 1 diabetes in the offspring of infants born to the same mother by different modes of delivery. The authors also found that mode of delivery was not only associated with childhood type 1 diabetes, but may also be associated with type 1 diabetes at any age, as well as all types of diabetes. However, most of these cases were type 1 diabetes cases, so the results of this study cannot be extrapolated to type 2 diabetes unless additional studies are conducted.