Summary: New research finds that low maternal vitamin D levels around 20 weeks of pregnancy are associated with a higher likelihood of autism-related traits in children by age six.
Source: University of Queensland
Researchers at the University of Queensland’s Queensland Brain Institute report an association between gestational vitamin D deficiency and increased autism-related traits in offspring.
A team led by Professor John McGrath, in collaboration with Dr Henning Tiemeier from Erasmus Medical Centre, analyzed maternal and neonatal blood samples and developmental follow-up data to investigate whether prenatal vitamin D status relates to later autism-related characteristics. The study found that women with low vitamin D at roughly 20 weeks’ gestation were more likely to have children who scored higher on measures of autism-related traits when assessed at about six years of age.
Professor McGrath said the findings strengthen growing evidence that vitamin D is important for brain development, not only for bone health. “This study adds to the evidence linking low vitamin D during pregnancy with altered neurodevelopment,” he explained. “While more research is needed, it raises the possibility that safe, affordable prenatal vitamin D supplementation in at-risk groups could reduce a potentially preventable risk factor for autism-related outcomes.”
Vitamin D is produced in the skin after sun exposure and is also available from certain foods and supplements. The researchers emphasize that recommending increased sun exposure is not a safe public health strategy in sun-intense regions, due to the skin cancer risk. Instead, targeted, low-cost supplementation may be a more practical approach for improving maternal vitamin D levels during pregnancy.
The analysis drew on the Generation R Study, a long-term population cohort based in Rotterdam, The Netherlands. Approximately 4,200 blood samples from mothers and their children were examined alongside developmental assessments. Vitamin D status was measured as serum 25-hydroxyvitamin D (25OHD) from maternal mid-gestation and from cord blood at birth. The investigators defined deficiency as 25OHD concentrations under 25 nmol/L and compared outcomes to those with sufficient levels (greater than 50 nmol/L).
Analysis showed that children whose mothers were vitamin D deficient in mid-gestation had higher (more atypical) scores on the Social Responsiveness Scale (SRS) at age six. The association remained significant after accounting for factors such as ancestry, genetic sample structure, the season when blood was collected, and when vitamin D was treated as a continuous measure rather than a categorical one. Results were consistent whether maternal mid-gestation levels or neonatal cord blood levels were used, although the strongest signal was observed for mid-gestation maternal levels.
Autism spectrum disorder (ASD) covers a range of lifelong neurodevelopmental conditions characterized by difficulties in social communication, interaction, and flexible thinking. Researchers often study autism-related traits as continuous measures in population cohorts because these traits can reveal risk patterns shared with clinical ASD while allowing analysis across a broader sample.
Professor McGrath’s team has previously reported links between low neonatal vitamin D and an elevated risk of schizophrenia, reinforcing the potential importance of vitamin D in early brain development. However, the authors caution that observational associations do not prove causation. Well-designed intervention trials are needed to confirm whether improving maternal vitamin D status can reduce autism-related outcomes.
Funding: The research was funded by the National Health and Medical Research Council (NHMRC).
Source: John McGrath, University of Queensland
Image source: Image adapted from the University of Queensland press release.
Original research: The study, titled “Gestational vitamin D deficiency and autism-related traits: the Generation R Study,” was published in Molecular Psychiatry and lists authors A. A. E. Vinkhuyzen, D. W. Eyles, T. H. J. Burne, L. M. E. Blanken, C. J. Kruithof, F. Verhulst, V. W. Jaddoe, H. Tiemeier, and J. J. McGrath. The published work describes associations between maternal and neonatal 25-hydroxyvitamin D concentrations and continuous measures of autism-related traits at age six.
Gestational vitamin D deficiency and autism-related traits: the Generation R Study
There is strong interest in identifying modifiable prenatal risk factors for autism-spectrum disorders (ASD). Autism-related traits, measurable on a continuous scale, can help reveal population-level associations that inform understanding of ASD risk. Based on growing evidence that gestational vitamin D deficiency affects brain development, this exposure was tested as a candidate risk factor in a large population cohort (n = 4,229). Maternal mid-gestation and neonatal cord blood 25-hydroxyvitamin D (25OHD) concentrations were measured, with deficiency defined as <25 nmol/L and sufficiency as >50 nmol/L. Compared to the sufficient group, individuals in the deficient group had higher Social Responsiveness Scale (SRS) scores (maternal mid-gestation n = 2,866, β = 0.06, P < 0.001; cord blood n = 1,712, β = 0.03, P = 0.01). These findings held after restricting analyses to participants of European ancestry, adjusting for genetic sample structure, modeling 25OHD as a continuous variable, and correcting for season of blood sampling. The results point to gestational vitamin D deficiency as a potentially modifiable risk factor associated with autism-related traits that merits further investigation through interventional trials.
The study highlights a possible public health implication: because vitamin D deficiency during pregnancy is preventable with safe, inexpensive supplements, targeted strategies to improve prenatal vitamin D status in at-risk groups deserve further clinical evaluation.