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7 percent less likely to get immune mediated disease if born in the fall – July 2012

Month of birth, vitamin D and risk of immune mediated disease: a case control study

Giulio Disanto, George Chaplin, Julia M Morahan, Gavin Giovannoni, Elina Hypponen, George C Ebers and Sreeram V Ramagopalan
BMC Medicine 2012, 10:69 doi:10.1186/1741-7015-10-69 ; Published: 6 July 2012

Background
A season of birth effect in immune-mediated diseases (ID) such as multiple sclerosis and type 1 diabetes has been consistently reported. We aimed to investigate whether season of birth influences the risk of rheumatoid arthritis, Crohn's disease, ulcerative colitis and systemic lupus erythematosus in addition to multiple sclerosis, and to explore the correlation between the risk of ID and predicted ultraviolet B (UVB) light exposure and vitamin D status during gestation.

Methods
The monthly distribution of births of patients with ID from the UK (n = 115,172) was compared to that of the general population using the Cosinor test. Predicted UVB radiation and vitamin D status in different time windows during pregnancy were calculated for each month of birth and correlated with risk of ID using the Spearman's correlation coefficient.

Results
The distributions of ID births significantly differed from that of the general population (P = 5e-12) with a peak in April (odds ratio = 1.045, 95% confidence interval = 1.024, 1.067, P <0.0001) and a trough in October (odds ratio = 0.945, 95% confidence interval = 0.925, 0.966, P <0.0001). Stratification by disease subtype showed seasonality in all ID but Crohn's disease. The risk of ID was inversely correlated with predicted second trimester UVB exposure (Spearman's rho = -0.49, P = 0.00005) and third trimester vitamin D status (Spearman's rho = -0.44, P = 0.0003).

Conclusions
The risk of different ID in the UK is significantly influenced by the season of birth, suggesting the presence of a shared seasonal risk factor or factors predisposing to ID. Gestational UVB and vitamin D exposure may be implicated in the aetiology of ID.
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Provisional PDF is attached at bottom of this page


See also VitaminDWiki

Attached files

ID Name Comment Uploaded Size Downloads
1444 Immune disease vs month of birth.pdf PDF admin 07 Jul, 2012 22:32 1.70 Mb 643
1443 Odds ratio vs month.jpg admin 07 Jul, 2012 22:31 22.59 Kb 832
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