In the huge mega-analyses they have done to find the commonalities between people with MS, one in particular has puzzled researchers a lot. People with MS have a hugely disproportionate brith rate in the month of May over the month of November, which is the loswest for people with MS.. For a long time this merely sat as an oddity that was seen in all such surveys. Of course, people with MS' birthmonths represent all of the months, but there is that high and low in May and November.
Recently I have heard some interesting theories on it. The one that makes the most sense to me is that if you draw a connection to MS and Vitamin D levels growing up you might be able to explain it. Remember that many are now proposing that VitD levels are the critical problem connected with growing up in higher latitudes. The farther away you are from the equator, the less the sunshine penetrates the atmosphere, the cooler it is the more you cover your skin, and the less time the sun shines both during the year and during the day.
A baby born during November would have been maximally exposed to sunshine (through the mother) from late spring thru summer and into fall. Thus, one would expect that maternal Vit D levels would be highest in that month and then passed onto the newborn. It would also give the baby the best chance at higher vitamin D stores. This would give baby a "leg up" for lifetime Vit D levels. Conversely, if born in May, most of a baby's gestation would have taken place during the months of least sunshine. Now, this is only theory, but it is tantalizing isn't it?
I believe there are several prospective studies looking at maternal vitamin D levels to see if the first part of this hypothesis is even true.
It makes me want to have parents ensure that their kids do get adequate sun exposure and get their Vit D levels checked periodocally. Newer recommendations are that the levels should be at least over 30. This has been raised from (I believe) 115. For adults with a higher risk for developing MS I would recommend levels closer to 50.
Jennie asked me about this, so I thought I would share here.
Quix