Respiratory symptoms in Queensland schoolchildren: an association between month of birth and respiratory illness

We have examined the relationship between month of birth and episodes of wheezing, productive cough, eczema and hayfever, and also standardized maximum mid-expiratory flow (FEF25-75) in a representative sample of 4549 Australian primary schoolchildren (mean age 10.1 years). Children experiencing frequent wheezing (one or more episodes per month) were more likely to be born in spring and summer (odds ratio = 1.6, 95% confidence interval = 1.1-2.4), but this was not seen for less severe disease. No effect of season or birth month was seen for the other illnesses examined or for lung function.