Association between cesarean delivery and childhood allergic diseases in a longitudinal population-based birth cohort from Japan.

The association between cesarean delivery and childhood allergic diseases, such as atopic dermatitis, food allergy, and bronchial asthma, remains unclear, with limited evidence from Asian populations. We analyzed population-based data of 2,114 children born in Japan in 2010 from the Longitudinal Survey of Babies in the 21st Century, linked to the Perinatal Research Network Database. Comparisons were made between children born by cesarean delivery and those born vaginally. Longitudinal outcomes were atopic dermatitis, food allergy, and bronchial asthma during childhood for each age group up to 9 years of age. We performed Poisson regression analyses with robust variance, and adjusted for child and parent variables, followed by supplementary analyses using generalized estimating equations (GEE). Children born by cesarean delivery did not have a higher risk of most outcomes compared to those born vaginally. GEE analysis found no association between cesarean delivery and atopic dermatitis (adjusted risk ratio [aRR] 0.8, 95% confidence interval [CI] 0.5-1.2), food allergy (aRR 1.1, 95% CI 0.7-1.7), bronchial asthma (aRR 1.0, 95% CI 0.8-1.4), or allergic rhinoconjunctivitis (aRR 0.9, 95% CI 0.8-1.1). This study shows no clear evidence of an association between delivery mode and childhood allergic diseases in Japan.