The importance of prenatal exposures on the development of allergic disease: a birth cohort study using the West Midlands General Practice Database

Using a birth cohort of 24,690 children, derived from the West Midlands General Practice Research Database, the authors investigated a number of perinatal exposures on the incidence of asthma, eczema, and hay fever. Their findings suggest that exposure to antibiotics in utero is associated with an increased risk of asthma in a dose-related manner (more than two courses of antibiotics compared with none adjusted hazard ratio [HR] 1.68; 95% confidence interval [CI], 1.51-1.87), and similar associations are present for eczema (adjusted HR 1.17; 95% CI, 1.06-1.29) and hay fever (adjusted HR 1.56; 95% CI, 1.22-2.01). Exposure to a range of infections in utero was also associated with a small increased risk of developing allergic disease. Strong protective effects of older siblings on the incidence of allergy are present within this cohort, but previous pregnancies that did not result in a live birth were not protective. These findings suggest that exposure to antibiotics and to infections in utero is a potentially important risk factor in the development of allergic disease.