Birth-related exposures and asthma and allergy in adulthood: a population-based cross-sectional study of young adults in North Staffordshire.

The rise in the prevalence of asthma and other allergic disorders over the past two decades has been well documented, yet this increase has still to be fully explained. One possible hypothesis is that the rise in atopic disease is related to recent changes in obstetric practice. Using a population based survey, with linked general practice and hospital birth records, we investigated the association between 6 birth related exposures (birth weight, mode of delivery, artificial commencement of labour, prematurity, neonatal intensive care unit admission and foetal distress) and asthma, allergic rhinitis, eczema and hay fever in adulthood. No statistically significant associations were demonstrated between any of the birth-related exposures and the 4 allergic conditions studied, although some non-significant trends were noted, especially for those born by Caesarean section (asthma: odds ratio 1.71, 95% confidence interval 0.75, 3.86, eczema: 1.09, 95% CI 0.41, 2.91, hay fever: OR 1.36, 95% CI 0.51, 3.61) (Table 2) or having evidence of foetal distress during labour (asthma: OR 1.45, 95% CI 0.70, 3.02, rhinitis OR 2.82, 95% CI 0.87, 9.15, hay fever OR 1.34, 95% CI 0.57, 3.14). Given the ongoing changes in obstetric practice and the continuing rise in the prevalence of allergic disorders, this area is worthy of further investigation.