A December 2020 study by the University of Queensland finds that there may be a link between vitamin D deficiency during pregnancy and autism spectrum disorder in boys.

The researchers found “…vitamin D deficiency during pregnancy caused an increase in testosterone in the developing brain of male rats … The biological cause of Autism spectrum disorder (ASD) is unknown but we have shown that one of the many risk factors--low vitamin D in mothers--causes an increase in testosterone in the brain of the male foetuses, as well as the maternal blood and amniotic fluid…In addition to its role in calcium absorption, vitamin D is crucial to many developmental processes…Our research also showed that in vitamin D-deficient male foetuses, an enzyme which breaks down testosterone was silenced and could be contributing to the presence of high testosterone levels.”