Data Science

Could vitamin D levels in pregnant women be linked to learning disabilities?

Researchers looked at the data of over 800,000 children in Scotland to see whether there is a link between the time of year children are conceived in and learning disabilities.

Photo of pregnant woman sitting on a park bench

School of Health and Wellbeing research theme 

Data Science

University of Glasgow beacons

Addressing Inequalities

The challenge

Previous studies suggest that there could be a link between autism and the time of year children are conceived. However, no research has been done into a possible connection with other learning disabilities.

The research

Researchers from the University of Glasgow, the NHS and the Scottish Government linked two databases: The Scottish annual pupil census (2006–2011) and a maternity database that contains information about all women giving birth in Scottish hospitals. Through this data linkage they were able to find out when more than 800,000 children included in the study were born and whether they have a learning disability.

The results

The research team found that 8.9% of children who had been conceived between January and March had learning disabilities. In contrast this figure was only 7.6% for children who had been conceived between July and September.

The impact

In Scotland, there is insufficient sunlight in January to March for pregnant mothers to produce vitamin D. The researchers think that this lack of vitamin D could therefore be a cause for children conceived in winter being more likely to have a learning disability than children conceived in summer.

The results of this study show that if we could get rid of the seasonal differences, we could prevent 11% of cases of learning disabilities.

Although the study did not directly measure vitamin D, it remains perhaps the most likely explanation for the trend. If it is indeed the cause, it would greatly support the recommendation by the government that all pregnant women (and women who are trying to get pregnant) take vitamin D supplements.

Find out more about learning disabilities


Professor Jill Pell


Mackay, D. F., Smith, G. C. S., Cooper, S., Wood, R., King, A., Clark, D. N., & Pell, J. P. (2016). Month of Conception and Learning Disabilities: A Record-Linkage Study of 801,592 Children. American Journal of Epidemiology, 184 (7), 485-493.

This case study is featured in the Farr Institute "100 Ways of Using Data to Make Lives Better" series.