Association of cesarean section with asthma and atopic dermatitis in infants from the Japan Environment and Children's Study.

Recently, the rates of allergic diseases and cesarean delivery have increased worldwide. Some reports describe associations between allergic diseases and cesarean delivery. However, the association between allergic diseases and cesarean delivery is controversial. In this study, we investigated the association between cesarean delivery and the development of wheezing and eczema among infants at 1 year of age. We used data including those of 104,065 fetal records and their children from the Japan Environment and Children's Study. Information about the mode of delivery, wheezing, eczema, asthma, and atopic dermatitis was obtained from medical record transcripts and questionnaires. Multiple logistic regression analysis was performed to determine the risks of wheezing, eczema, asthma, and atopic dermatitis among infants at 1 year of age associated with cesarean delivery. We included 74,639 subjects in this study, wherein 18.4% underwent cesarean deliveries. Children born by cesarean delivery had no increased odds of developing wheezing (adjusted odds ratio [aOR] = 0.98; 95% confidence intervals [CI, 0.93-1.04], eczema (aOR = 0.99; 95% CI, 0.94-1.05), asthma (aOR = 0.95; 95% CI, 0.84-1.08), or atopic dermatitis (aOR = 1.02; 95% CI, 0.92-1.13).