Summer born babies more at risk of multiple sclerosis, says research

By Dr. Ananya Mandal, MDApr 30 2010

A recent study in Australia has found a link between low exposure to sunlight during the first three months of pregnancy and development of multiple sclerosis (MS) later in life of the baby.

The linking factor here say researchers is low Vitamin D. The lack of this vitamin may lead to damage to the nervous system and immune system of the unborn baby and lead to MS later in life. MS is a severely debilitating disorder seen further off the equator. It deals with a hyperactive immunity that destroys the protective sheath around nerves and causes progressive paralysis of all muscles, loss of sensation and even vision.

For the study the team of scientists reviewed birth records of 1,524 MS patients born between 1920 and 1950, and found there were more of them born in the months of November and December. This meant that the first three months of pregnancy fell between the winter months of April to June when most mothers expecting a baby would be indoors to ward off the cold. On the other hand MS patients born in May and June - meaning their first trimesters were in the early summer months of September to November were a smaller number.

The scientists wrote, “The risk of multiple sclerosis was around 30 percent higher for those born in the early summer months of November and December compared to the months of May and June.” Judith Staples and Lynette Lim at the Australian National University in Canberra and Professor Anne-Louise Ponsonby at the Murdoch Children’s Research Institute were the lead researchers.

Their work was published in the British Medical Journal on Friday. They also wrote, “Vitamin D supplementation for the prevention of multiple sclerosis might also need to be considered during in utero development.” These findings were correlated with previous studies in the northern hemisphere which found more cases of MS among people born in May, whose mothers probably had little exposure to sunlight in their first trimester during the colder months of September to November.

It is found in previous studies that more than 60% of UK residents have lower levels of vitamin D, with worst sufferers in Scotland, the North of England and among ethnic minorities. This makes UK a leader in this aspect. The Food Standards Agency says that sun should be enough to provide all the necessary Vitamin D. “Taking 25 micrograms (0.025 mg) or less of vitamin D supplements a day is unlikely to cause any harm,” they said but just 15 minutes of sun exposure can provide 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.

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