Season of birth and multiple sclerosis in Sweden
Article first published online: 23 NOV 2009
Copyright © 2009 The Authors. Journal compilation © 2009 Blackwell Munksgaard
Acta Neurologica Scandinavica
Volume 121, Issue 1, pages 20–23, January 2010
How to Cite
Salzer, J., Svenningsson, A. and Sundström, P. (2010), Season of birth and multiple sclerosis in Sweden. Acta Neurologica Scandinavica, 121: 20–23. doi: 10.1111/j.1600-0404.2009.01181.x
- Issue published online: 15 DEC 2009
- Article first published online: 23 NOV 2009
- Accepted for publication February 9, 2009
Vol. 122, Issue 1, 70–73, Article first published online: 15 JUN 2010
- month of birth;
- multiple sclerosis;
- season of birth;
- vitamin D
Objective – To estimate the risk of multiple sclerosis (MS) by month of birth in Sweden.
Materials and Methods – Cases (n = 9361) were obtained from the Swedish MS Registry. All births in Sweden 1900–2007 served as controls (n = 12,116,853). The risk of MS was analyzed for each month of birth separately compared with birth during the other 11 months.
Results – More (11%) cases with MS than expected were born in June. Fewer (8% and 10%) cases with MS than expected were born in December and January (non-significant after correction for multiple analyses). More (5%) cases with MS than expected were born in February–July as compared with August–January.
Conclusions – This study supports previous results suggesting an association between the risk of MS and the season of birth. Decreased exposure to sun in the winter leading to low vitamin D levels during pregnancy is a possible explanation that needs further research.