Mother's sun exposure linked to multiple sclerosis

Children born in the summer have a higher chance of developing Multiple Sclerosis (MS) later in life than those born in the winter, according to a new study.

The Australian study found that there was a 30% higher risk of developing MS for those born in the early Australian summer months of November and December compared to the winter months of May and June.

These findings echo similar results for other studies of the same effect in the northern hemisphere which found an increase in MS for babies born in May compared to those born in November.

There has long been speculation that lack of sunlight exposure is a contributing factor to MS rates, with northern European countries having higher rates than southern European countries (Scotland and Sweden have particularly high rates).

In the study the research team analysed data on the number of patients with MS born in Australia compared to other births for each birth month of every year from 1920 to 1950 by sex and region of birth.

By comparing this to known variations in ultraviolet radiation levels in Australia by region and season, they were able to establish links between sunlight exposure and MS rates.

They found that the risk of multiple sclerosis was around 30% higher for those born in the early summer months of November and December compared to the months of May and June.

Another finding was that the region of birth was a factor, implying that early childhood exposure to sunlight also plays a part in MS risk.

The study was carried out by a team at the Murdoch Children’s Research Institute in Melbourne and is published in the British Medical Journal’s website bmj.com.

This article was published on Fri 30 April 2010