A prospective epidemiological study based on 4229 children and their mothers showed that gestational vitamin D deficiency was associated with increased autism-related traits in 6-year-old children.1 The study population was part of the Generation R Study—consisting of a large, ethnically diverse cohort, designed to identify early environmental and genetic causes of normal and abnormal health related outcomes in mothers and their children.
Researchers from the University of Queensland (Australia) and the Erasmus Medical Centre (the Netherlands) measured women’s serum 25-hydroxyvitamin D (25OHD) concentration at two time points during their pregnancy: first at mid-gestation around 21 weeks and then at birth at around 40 weeks (from cord blood). When the children were around 6 years old, the parents filled out the Social Responsiveness Scale (SRS)—a validated questionnaire designed to assess the child’s behavioral features related to social cognition, social communication and autistic mannerisms.2
The study found that, compared with those who were vitamin D sufficient (defined as serum 25OHD ≥50 nmol/L) during pregnancy, women who were overtly vitamin D deficient (serum 25OHD <25 nmol/L) were more likely to have a child with autistic-related traits as indicated by significantly higher SRS scores. This association was more noticeable in mothers who were vitamin D deficient at both time points (mid-gestation and at time of birth). Professor JJ McGrath of the Queensland Brain Institute at the University of Queensland, corresponding author of this study, suggested that infants exposed to persistent low vitamin D from mid-gestation until birth may be at risk for autism-related traits.
The study results were published in the journal Molecular Psychiatry (November 2016).
Why is this clinically important?
The finding of this study has important implications from the public health standpoint.
First, vitamin D deficiency among pregnant women is common. Among the Generation R Study cohort, 16% of the pregnant women were vitamin deficient mid-gestation (~21 weeks) and the number increased to 36% ~40 weeks. In the United States, approximately 1 in 4 women of childbearing age were at risk of vitamin D inadequacy and 1 in 12 women of childbearing age were at risk of vitamin D deficiency.3
The fetus depends entirely on the mother for vitamin D supply. Maternal vitamin D deficiency is not only associated with impaired fetal skeletal formation causing infant rickets and reduced bone mass, but also strongly associated with childhood vitamin D deficiency which has been linked to increased risk of respiratory infection, asthma, type 1 diabetes, and schizophrenia.3
Second, the remedy is simple. Study investigators suggest regular prenatal supplementation with vitamin D may help correct existing maternal vitamin D deficiency, and thus may help reduce the incidence of autism-spectrum disorder in the child.
- Vinkhuyzen AA, Eyles DW, Burne TH, et al. Gestational vitamin D deficiency and autism-related traits: the Generation R Study. Mol Psychiatry 2016.
- Constantino JN, Davis SA, Todd RD, et al. Validation of a brief quantitative measure of autistic traits: comparison of the social responsiveness scale with the autism diagnostic interview-revised. J Autism Dev Disord 2003;33:427-33.
- Zhao G, Ford ES, Tsai J, Li C, Croft JB. Factors Associated with Vitamin D Deficiency and Inadequacy among Women of Childbearing Age in the United States. ISRN Obstet Gynecol 2012;2012:691486.