THURSDAY, April 29 (HealthDay News) -- When and where people are born may affect their odds of developing multiple sclerosis, according to researchers who found that children born in the early summer months in the Southern Hemisphere are more likely to develop multiple sclerosis than those born in early winter.
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A similar pattern has been found in the Northern Hemisphere, where the summer and winter months are the reverse of those in the Southern Hemisphere. The researchers think the higher disease rates may have something to do with the children's mothers getting less exposure to sunlight during pregnancy.
Scientists have linked low vitamin D levels to higher rates of multiple sclerosis, and sunlight boosts vitamin D levels.
In the new study, published online April 29 in BMJ, Anne-Louise Ponsonby, of the Murdoch Children's Research Institute at Royal Children's Hospital in Melbourne, and her colleagues analyzed data on children with multiple sclerosis born in Australia from 1920 to 1950. They tried to find links to the levels of sunlight in the regions in which the mothers lived.
The risk was about 30% higher for those born in November and December, which are early summer months in the Southern Hemisphere, compared with those born in the early winter months of May and June, the study found. Babies were more likely to have multiple sclerosis if their mothers had low exposure to sunlight from five to nine months before giving birth.
The study authors wrote that researchers need to analyze the idea of giving vitamin D supplements to pregnant mothers to help prevent multiple sclerosis.
-- Randy Dotinga
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SOURCE: BMJ, news release, April 29, 2010