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Month of birth, vitamin D and risk of immune mediated disease: a case control study Full Text
BMC Medicine, 07/18/2012
Clinical Article
Disant G et al. – 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 immune–mediated diseases (ID). Gestational ultraviolet B (UVB) and vitamin D exposure may be implicated in the aetiology of ID.
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.
- 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).