A quarterly publication of the Autism Research Institute

The Autism Research Review International is quarterly publication of the Autism Research Institute

Winter, 2021 | Number 1, Volume 35

Maternal vitamin D deficiency may increase fetal testosterone

A number of studies implicate low vitamin D levels in utero as a factor in autism spectrum disorders (ASD), and a new study suggests that male children of vitamin D deficient women have an increased likelihood of having ASD because this deficiency leads to an increase in testosterone in their developing brains. 

Research also indicates that fetal testosterone levels are elevated in children who later develop ASD. In addition, the 3-to-1 ratio of males to females in ASD suggests that male hormones play a key role in the condition. However, the new study is the first to link low vitamin D and elevated testosterone. 

In the study, Asad Amanat Ali and colleagues, including senior researcher Darryl Walter Eyles, fed female rats a vitamin D deficient diet before and during pregnancy and then collected tissues from their embryos. The researchers report that maternal vitamin D deficiency led to increases in testosterone levels in the mothers’ blood. In addition, they say, testosterone levels were elevated in the brains of male offspring of the vitamin D deficient mothers. 

Furthermore, Eyles notes, “Our research… showed that in vitamin D-deficient male fetuses, an enzyme which breaks down testosterone was silenced and could be contributing to the presence of high testosterone levels.” 

Levels of testosterone and androstenedione (another sex steroid) were elevated in the amniotic fluid of female but not male fetuses of vitamin D-deficient mothers. However, female fetuses did not exhibit increased testosterone in their brains. 

The researchers conclude, “This study is the first to show how an epidemiologically established environmental risk factor for ASD [low vitamin D] may selectively elevate testosterone in male embryonic brains. These findings provide further mechanistic support for the prenatal sex steroid theory of ASD.”

Ali and colleagues say their findings provide further support for the prenatal sex steroid theory of ASD.


“Developmental vitamin D deficiency increases foetal exposure to testosterone,” Asad Amanat Ali, Xiaoying Cui, Renata Aparecida Nedel Pertile, Xiang Li, Gregory Medley, Suzanne Adele Alexander, Andrew J. O. Whitehouse, John Joseph McGrath, and Darryl Walter Eyles, Molecular Autism, December 2020 (free online). Address: Darryl Walter Eyles, [email protected]


“Vitamin D the clue to more autism spectrum disorder in boys,” news release, University of Queensland, December 11, 2020.