Neonatal vitamin D status in relation to autism spectrum disorder and developmental delay in the CHARGE case-control study.

This was an observational case-control study, so it cannot show that vitamin D caused or prevented autism or developmental delay. Vitamin D was measured only once from newborn blood spots, not at other pregnancy periods that may matter. The sample had relatively high vitamin D levels, with only 23% deficient. It may not have enough very low levels to detect a strong effect. Several positive findings were subgroup or post-hoc analyses, including sex and race/ethnicity. These findings need confirmation. The sample included 595 male and 130 female children, and 566 white children among 723 with race information. This limits generalization. Adjustment for maternal education and pre-pregnancy BMI removed the crude developmental delay association. This creates uncertainty about confounding or mediation. Children with Down syndrome may have lower vitamin D because of their condition, not because low vitamin D caused their developmental delay. Post-hoc severe deficiency findings were reported inconsistently in the results and discussion.

The article lists research support from NIH, non-U.S. government, and U.S. government (non-PHS). Dr. Schmidt received travel and lodging for meetings and Autism Speaks grant funding to develop an online autism environmental questionnaire. No other authors declared conflicts.

Do not conclude that vitamin D supplementation during pregnancy or infancy reduces autism or developmental delay. This was an observational study of archived newborn blood spots, not a treatment trial, and the main autism finding was null.