Birth month and risk of atopic dermatitis: A nationwide population-based study

Background: An individual's birth month has been associated with allergic diseases, but little is known about the association between birth month and atopic dermatitis (AD). Objective: The aim of this study was to investigate the risk of AD in children born in various months. Methods: Using Taiwan's National Health Insurance Research Database, we conducted a case-control study that included 31 237 AD cases and 124 948 age- and gender-matched controls without AD. Data regarding sociodemographic factors and coexisting medical conditions were collected and controlled in the multivariate logistic regression to determine the adjusted odds ratios and 95% confidence intervals for AD associated with the participant's birth month. Results: Compared with people born in May, people born in December had the highest risk of AD (OR 1.17, 95% CI 1.10-1.25), followed by people born in October (OR 1.15, 95% CI 1.08-1.22) and November (OR 1.13, 95% CI 1.06-1.20). Low income (OR 1.28), asthma (OR 1.88), allergic rhinitis (OR 1.70), psoriasis (OR 2.36), vitiligo (OR 1.99), urticaria (OR 2.14), and systemic lupus erythematosus (OR 1.91) were significant coexisting medical conditions associated with AD. Conclusion: Being born in December, October, or November may be associated with an increased risk of AD. Future investigations are needed to evaluate the possible mechanism behind the association between birth month and AD. © 2016 John Wiley & Sons A/S.