Maternal Vitamin D Levels During Pregnancy and Offspring Autism Spectrum Disorder.

Abstract Background Findings from previous studies on maternal 25(OH)D levels during pregnancy and offspring autism spectrum disorder (ASD) are inconsistent. Methods The association between maternal 25(OH)D levels during pregnancy and offspring ASD was examined using a nationwide population-based register data with a nested case-control study design. The ASD cases (n=1558) were born from 1987 to 2004, who received a diagnosis of ASD by 2015, and were matched with equal number of controls. Maternal 25(OH)D levels during pregnancy were measured using quantitative immunoassay from maternal sera, collected during the first and early second trimesters and archived in the national biobank of the Finnish Maternity Cohort. Conditional logistic regression examined the association between maternal 25(OH)D levels and offspring ASD. Results In the adjusted model, there was a significant association between increasing log-transformed maternal 25(OH)D levels and decreasing risk of offspring ASD (adjusted odds ratio (aOR) 0.75, 95% CI 0.62-0.92, p=0.005). Analyses by quintiles of maternal 25(OH)D levels revealed increased odds for ASD in the two lowest quintiles: Conclusion This finding has implications for understanding the role of maternal vitamin D during fetal brain development and increased risk of ASD.