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Autism and vitamin D in pregnancy

by on 2018/03/23

This post was written by Amanda Gillooly and Sinead Rhodes

Autism Spectrum Disorder (ASD) is a developmental disorder associated with difficulties in social communication and social interactions and an engagement in restrictive and repetitive behaviours. Media coverage regarding childhood disorders and risk factors associated with their development has increased significantly in recent years. While this increased awareness can have clear advantages, this can also lead to heightened and at times unwarranted anxiety among parents. This week the media has reported on evidence of a link between vitamin D deficiency in pregnancy and the development of autistic behaviours in children. Headlines have included “children born to mothers with low vitamin D levels may develop autistic-like behaviours”), “low vitamin D linked to autism behaviours” and the more stronger assertion “vitamin D deficiency can put children at risk of autism”. These headlines suggest a link between vitamin D deficiency and the development of autism. The use of phrases such as “at risk”, potentially make these headlines alarming to pregnant mothers. Here, we will delve further into the actual research study behind the headlines, to clarify precisely what the study showed and the context of this research.

What did this study do?

Researchers from the University of Western Australia and the Telethon Kids Institute conducted the study using a sample of rats. They examined the effects of a vitamin D deficiency during pregnancy and lactation (i.e. breast-feeding in humans) on the brain development, social behaviour and thought processes of the offspring (i.e. reflecting an infant’s response). The rats were split into two groups. One group of rats were placed on a vitamin D deficient diet and the other group were placed on a vitamin D rich diet for a period of 5 weeks prior to mating. Using a range of behavioural and what are known as cognitive tasks (that tap into thinking processes), the researchers assessed the brain function, social interaction skills and cognitive skills of the offspring. The researchers compared the performance of the rats between these two groups and reported that the rats in the vitamin D deficient group scored poorer than the rats in the vitamin D rich group. These differences were observed on a measure of social interaction skills and on a cognitive assessment which required them to switch their attention from one object to another.

How did the media handle reporting of this study?

Several positive aspects from the media’s reports on this subject are evident, including the clear use of a definition of autism spectrum disorder, the use of direct quotations from the research team and reference to the source of the original research article. As we have noted in the Research the Headlines “How to tips”, the use of direct quotes can reduce the risk of the research findings being misinterpreted. Openly stating the source of the original article provides the reader with the opportunity to look further than these brief media reports and draw their own conclusions about the study.

As this study involved the assessment of a sample of rats, it is important to be careful when making generalisations as to whether the findings cross over to human experience. To be able to conclude that this effect also applies to human infants, we would need to examine this directly. This would involve recruiting a sample of mothers who had a vitamin D rich diet prior to pregnancy and a sample of mothers who had a vitamin D deficient diet prior to pregnancy. By subsequently examining the social and cognitive skills of the infants between these two groups, we could then draw conclusions on whether vitamin D deficiency is linked with children’s development. The media articles we reviewed did acknowledge this need to take care when generalising the findings, however, this was often only noted at the end of the article. In order to reduce potential alarm among pregnant mothers, a headline which captures the nature of this animal research study would have been more appropriate. This is evident for example in a post published by the ‘Conversation’ where the authors used the headline “animal study hints at link between vitamin D and autism, but don’t start supplementing yet”.

Across some media reports there is also reference to the potential impact of these findings on pregnant mothers’ health and the need to consider ways to increase vitamin D supplements during pregnancy. This was a single research study which used a relatively small sample of 15 rats per group. In order to make interpretations which could inform health decisions replication of study findings is key. It is essential that further research studies are conducted to investigate the effects of vitamin D during pregnancy to see if these findings are replicated.


With health related articles attracting increased interest within the media, it is vitally important to interpret these findings with caution by looking further than these initial headlines. This will help readers to be more informed about the nature of the study and its findings and help to minimise undue anxiety.  This study seems to suggest a link between vitamin D and autism and points to the need for further research in this area.

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