About 22% of ASD Risk in Offspring Was Mediated Through Premature Birth
Previous research has shown that children born to mothers with Type 1 Diabetes (T1D) are at greater risk of developing autism. However, these earlier studies have not been able to decipher whether the risk is associated with pre-term birth, which affects approximately one-third of pregnancies with T1D, and whether maternal levels of glycated hemoglobin (HbA1c) impact the likelihood of offspring developing the disorder. To find these answers, a team of researchers conducted a cohort study of 1.4 million Swedish children born between 1998 and 2015. Of the children in the cohort, 8003 (0.6%) children were born to mothers with T1D, 24,941 (1.8%) were diagnosed with autism spectrum disorder (ASD), and 81,915 (5.8%) were born prematurely. As with previous research, after running a cohort analysis, this study found an increased risk of autism in offspring of mothers with T1D. To be confident of their finding, the research team also ran a detailed adjustment for individual and familial confounding. The results remained consistent. The team then conducted a mediation analysis of pre-term births and discovered that approximately 22% of the ASD risk was mediated due to pre-term delivery. After this discovery, the team turned their attention to maternal levels of HbA1c. The team analyzed T1D mothers who had information on their HbA1c levels and T1D mothers who did not have information on their HbA1c levels. No differences were discovered between the two groups in the analysis. Therefore, the researchers gathered that HbA1c is not associated with ASD risk beyond the risk linked with the T1D diagnosis itself. In the end, the authors acknowledge that the mechanism underlying the association between T1D and ASD remains unclear. They point to earlier research showing that hyperglycemia during fetal life could lead to permanent changes in neuronal networks. The team also calls attention to another study that claims hyperglycemia induces inflammation and oxidative stress, which are risk factors for ASD.
