Babies born in summer ‘more likely to develop multiple sclerosis’

From The Times April 30, 2010

Babies born in summer ‘more likely to develop multiple sclerosis’

David Rose 5 Comments
Recommend? (4) Babies born in the summer months have a higher risk of developing multiple sclerosis (MS) because their mothers do not get enough sun during pregnancy, a study says.

Mothers-to-be who failed to get enough sunshine — cutting off a main source of vitamin D — were nearly a third more likely to have offspring who developed MS, researchers from the Royal Children’s Hospital in Melbourne and the Australian National University claimed.

They said that exposure to sunlight in the first three to four months of pregnancy could affect how a baby’s central nervous and immune system developed. The study found that babies born in November and December (during the Australian summer) were 32 per cent more likely to develop MS than those born in May and June.

The research, published on the British Medical Journal’s website, looked at 1,524 patients with MS born between 1920 and 1950 and noted the month of birth and the region they were born in. They compared the data with levels of ultraviolet radiation across Australia.

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Babies born in early summer months had a higher risk of MS than those born in early winter. No link was found between exposure to sunlight in the last four months before a woman gave birth and risk of MS. But those women who had low sunlight exposure in the first three or four months of pregnancy had a higher risk of their child developing the condition.

The researchers said: “Our results show a trough in multiple sclerosis in people born in May-June, when a protective effect is evident, compared with a peak in those born in November-December, thus mirroring the northern hemisphere pattern of a peak associated with May.”

More than 60 per cent of the British population have “sub-optimal” levels of vitamin D, with the problem being worse in Scotland, the North of England and among ethnic minorities. Rates of MS in Scotland and other northern countries are also among the highest in the world.

Recent studies indicate that vitamin D supplements could help asthma sufferers who do not respond to the usual steroid treatment, while others say that it can protect against bowel cancer and heart disease.

The Food Standards Agency said that “most people should be able to get all the vitamin D they need from their diet and by getting a little sun”.

Just 15 minutes exposure to sunshine is enough to provide the body with the equivalent of 500 micrograms (0.5mg) of vitamin D. Pregnant or breastfeeding women, and people over 60 are advised to take 10 micrograms of vitamin D each day.

“Taking 25 micrograms (0.025 mg) or less of vitamin D supplements a day is unlikely to cause any harm,” the agency said.

Doug Brown, head of biomedical research at the MS Society, said: “These results add to the weight of existing evidence suggesting vitamin D plays a role in the development of MS.”