Babies whose mothers get less sunshine in pregnancy are at higher risk of developing MS in later life, warn researchers. The cause may be a lack of vitamin D in pregnant women’s blood, which is mainly manufactured from exposure to sunlight, at certain times of the year. British researchers are calling for pregnant women to be given vitamin D supplements to cut cases of the disease after carrying out the biggest study of its kind. It is thought that variations in vitamin levels could affect how a baby’s central nervous and immune system develops.
The new study found the chances of developing multiple sclerosis are five per cent higher among those born in April and May, compared to the average risk.
The risk of developing MS was 5-10 per cent lower for babies born during the months of October and November.
Nearly 100,000 people in the UK have MS, the most common disabling neurological condition affecting young adults.
Previous research shows high levels of vitamin D in the body may protect against the disease.
But the latest study compared data on almost 152,000 people with MS with expected birth rates for the disease to explore the effect of the month of birth on the risk.
Dr Sreeram Ramagopalan, of Queen Mary University of London, Blizard Institute, and colleagues, said the study provided the most compelling evidence so far to justify telling women to take vitamin D supplements during pregnancy.
He said ‘Around 90 per cent of women are vitamin D deficient during the winter months which means pregnant women are especially at risk.
‘Research has been pointing this was for years but this is the biggest study of its kind. It may only be a small effect but it is now proven.
‘Taking supplements of 1,000 iu (international units) of vitamin D a day cannot do pregnant women any harm, and it is likely to reduce the incidence of this devastating disease’ he added.
It is already known that MS cases are higher in countries like Britain which are further away from the equator with relatively low sunlight levels.
Diabetes, asthma and life-threatening heart disease in babies are also linked to low levels of vitamin D in early life.
The latest study pooled previously published data on month of birth and MS cases, and included countries such as Britain at latitudes 52 degrees and greater from the equator.
This means insufficiently strong ultraviolet light reaches the skin between October and March to manufacture enough vitamin D during the winter months.
The seasonal trends showed a significant rise in risk of MS among those born in April and May and a significantly lower risk for those born in October and November.
The findings are published in the Journal of Neurology, Neurosurgery and Psychiatry (must credit).
Official policy in the UK is that pregnant women should take a vitamin D supplement but few are actually advised by doctors and midwives to do so.
Dr Ramagopalan said the notion that vitamin D deficiency contributed to MS was first aired in the 1960s.
‘It was laughed at’ he said. ‘No one could believe a simple vitamin would have this sort of impact. It is only by consistent replication of studies showing a link that we can say it is a genuine one.
‘We believe the Government should get behind this and tell midwives and pregnant women that taking supplements can have health benefits for the baby’ he said.
Oliver Gillie of the Health Research Forum, who campaigns for greater awareness of vitamin D benefits, said many experts were convinced that vitamin D supplements could potentially protect against MS and other diseases in populations where sunshine levels were too low.
He said ‘The Government needs to ensure local authorities take this on board, it’s a very cheap way of improving health.’