This interesting study from the UK looked at the month of birth as a risk factor for MS, which has previously been hypothesised to be related to maternal vitamin D levels during pregnancy. They analysed data on month of birth from 151,978 MS patients compared to expected birthrates, to assess the relationship between latitude and the observed to expected birth ratio of MS patients for each month.
Results from this study showed a significant excess risk in those born in April and reduction in risk in those born in October and November. A significant relationship between latitude and the observed to expected ratio was demonstrated in December and borderline significance in May and August.Therefore, these results demonstrate month of birth has a significant effect on subsequent MS risk and the researchers think this is likely due to ultraviolet light exposure and maternal vitamin D levels.
Authors: Dobson R, Giovannoni G, Ramagopalan S
Source: J Neurol Neurosurg Psychiatry. 2012 Nov 14. [Epub ahead of print]
Read the abstract