Too little sunlight, specifically ultraviolet B exposure, in pregnancy may lead to a higher risk of learning disabilities in child, according to a study.
The study conducted by researchers at University of Glasgow found that there was a statistically significant relationship between lower ultraviolet B (UVB) exposure over the whole of pregnancy and the risk of learning disabilities.
The researchers looked at more than 422,500 school-age children from across Scotland and found that low UVB exposure during pregnancy was associated with risk of learning disabilities.
"Learning disabilities can have profound life-long effects on both the affected child and their family.
The importance of our study is that it suggests a possible way to prevent learning disabilities in some children," said professor Jill Pell, Director of the University of Glasgow's Institute of Health and Wellbeing and lead author of the study.
"Clinical trials are now needed to confirm whether taking vitamin D supplements during pregnancy could reduce the risk of learning disabilities," Pell said.
UVB, the chief cause of skin reddening and sunburn, exposure from sunlight is linked to the production of the essential nutrient vitamin D in the body.
During the antenatal period, the foetus undergoes rapid development and growth, making it susceptible to environmental exposures, with the potential of long-term consequences. Maternal UVB exposure promotes the production of vitamin D, which is important for normal brain development of a foetus.
The researchers also found a slightly stronger relationship with low UVB exposure in the first trimester, suggesting that early pregnancy may be the most vulnerable to the effects of insufficient UVB.
As a result of low levels of UVB radiation from sunlight, vitamin D deficiency is common over winter months in high latitude countries such as Scotland, with Scottish residents twice as likely to be vitamin D deficient than people living in other parts of the UK, the researchers said.
Of the 422,512 schoolchildren included in the study, 79,616 (18.8 per cent) had a learning disability, 49,770 (23.1 per cent) boys and 29,846 (14.4 per cent) girls.
The percentage of children with learning disabilities varied by month of conception, ranging from 16.5 per cent among children conceived in July, to 21.0 per cent among those conceived in February, March and April.
"Our study linked routinely collected health and education data with environmental data enabling us to study a very large number of children in a way that would not be possible using traditional methods," said Claire Hastie, who did the analysis.
The study was published in the journal Scientific Reports.