Does Lack of Sunlight in Pregnancy Increase the Risk for Multiple Sclerosis?

Low serum vitamin D levels have been associated with increased risk for multiple sclerosis (MS). Because people with MS are more likely to be born in the spring, maternal winter ultraviolet light exposure and serum vitamin D levels during gestation have been suggested as contributing factors to MS risk in offspring. Two recent studies assessed this issue.

Dobson and colleagues evaluated whether month of birth affected risk for MS among a total of 172,918 participants with MS, in a meta-analysis combining 10 studies. Among 89,059 participants considered by geographic location, significantly more people with MS than expected had been born in April, May, or June (odds ratio range, 1.06–1.11) and significantly fewer than expected had been born i…