It seems the scientific community is scrambling to find just one shred of indication of a source of autism. There have been a few recent studies with apparently promising correlations. But correlations (links) are not causal. It can be a number of factors in fact, and that kind of synergy is almost impossible to tease out.
In this case, a lack of vitamin D levels in 20 weeks pregnant mom was correlated with higher incidence of autism in the child at age 6. I have been sufficiently convinced of the importance and deficiency of Vitamin D3 and have hence become a big proponent of its supplementation. Vitamin D3 is made by the body following sun exposure, so most of us are not getting what we need through the winter months. In addition, the past several decades have seen an increased usage in sunblock that would lower the body’s ability to make D. However, I would need to see more evidence of this link and also know the strength and power of the relationship.