Research: time of birth effect is not linked to the variation in UV

EpubVerheul F et al. Fluctuations of MS births and UV-light exposure. Acta Neurol Scand. 2012 Sep 12. doi: 10.1111/ane.12007.

BACKGROUND: MSers are more frequently born in spring when compared to autumn. Fluctuation of UV-light has been hypothesized to drive this phenomenon.

AIM: To assess the correlation between fluctuation of sunlight and birth season in persons with MS.

METHODS: For this record-linkage study, we collected from the international MSBase and the Italian MS iMed-web databases the dates of birth of 11,415 MSers from 36 centres from 15 countries worldwide and compared these to dates of live-births from national registries. From all participating sites, we collected data on UV-light fluctuation and assessed its correlation with seasonal fluctuation in MS births.

RESULTS: Compared with the reference cohort, an increased proportion of MSers were born in spring and a decreased proportion in autumn (odds ratio (OR) to be born in spring versus autumn = 1.158, χ(2 ) = 36.347, P < 0.001). There was no significantly increased fluctuation of MS births with increased quartile of ambient UV-light fluctuation (P(trend ) = 0.086).

CONCLUSION: Seasonal fluctuation of MS births as found in this worldwide cohort of patients with MS did not correlate with variation in seasonal fluctuation of UV-light. Most likely, it results from a complex interplay between fluctuation of sunlight, behavioural factors, other environmental factors and (epi)genetic factors.

"The results of this study support the month-of-birth effect, but question the link to UV fluctuation. Unfortunately, this study cannot take into account cultural factors that affect UV exposure and vD, for example indoor vs. outdoor activity, use of sunblock, fish consumption and the taking of vitamin supplements. Despite this  there is a trend in the data that suggest the greater your seasonal  UV variation (the difference between summer and winter) the greater the season variation in MS births. The pink dots above, in the the upper quartile of UV radiation fluctuation, seem to be the outliers; these are from Napoli in Italy and Beer Yaakov in Israel. It would be interesting to look at these regions in more detail. 

This study's data, however, still supports the latitude-vD hypothesis for month-of-birth effect. Why is this important? It is very important and one of the main bits of evidence we are using to underpin  the vD prophylaxis campaign to prevent MS. Our message stays the same; if you are planning to have a baby or are pregnant please make sure you are vitamin D replete. Prevention is better than cure!"

Other posts of interest:

27 Aug 2012
This month of birth effect is now being attributed to the effect of low vitamin D levels in the womb. The low vitamin D affects how the immature immune system develops. In other words if your mother was pregnant during winter, ...
14 Jun 2011
The month of birth and risk of MS are associated, more so in familial cases, implying that there is some interactions between genes and environment that may be related to climate. Such interactions may act during gestation or ...

14 Jun 2012
They tested whether variation in UVR as determined by seasons (short term variation) and solar cycles (long term variation) is related to MS birth month and to survival as measured by lifespan. Methods: Cases were selected ...
08 Jun 2012
The place of birth effect (preponderance for more Msers from the North verses the South USA) and month of birth effect (higher in May than November) was not evident. The place of Birth effect had been noticed previously in ...
16 May 2012
Month of birth has been associated with susceptibility to MS. It has been suggested that exposure to vitamin D, via sunlight may account for this difference that is having an influence in the womb. This study suggests that ...

12 Oct 2011
Vitamin D deficiency in pregnancy is very likely to be an important risk factor and may explain the month of birth effect; i.e. if you mother was pregnant during winter (last 6 months) and you were born in April you are at ...
19 Jan 2012
If part of the vitamin D effect is in utero (in the womb), as could be suggested by the month of birth effect. Then the issue of vitamin D levels in MSers at onset etc may be irrelevant. This adds an extra level of complexity. Sunday ...
23 Sep 2011
Vitamin D Deficiency and Latitude and Month of Birth. These are probably linked to sunshine which makes Vitamin D in humans. You get less ... This lack of vitamin D may shape how your immune system develops. This may .