Is delivery by cesarean section a risk factor for food allergy?

Background: Cesarean delivery might delay the colonization of the newborn intestine. A delayed or aberrant colonization process has been offered as an explanation for the increase in allergic diseases. Objective: The aim of this study was to examine whether cesarean delivery and the use of antibiotics were associated with subsequent food allergy. Methods: In a population-based birth cohort of 2803 children, information regarding mode of delivery, maternal or infant use of antibiotics, and information on potential confounders was obtained prospectively from parental reports and the Norwegian Birth Registry. Parentally perceived reactions to egg, fish, or nuts, as well as objectively confirmed reactions to egg at the age of 21/2 years, were chosen as outcomes. Results: Among children whose mothers were allergic, cesarean section was associated with a 7-fold increased risk of parentally perceived reactions to egg, fish, or nuts (odds ratio, 7.0; CI, 1.8-28; P = .005) and a 4-fold increased risk of confirmed egg allergy (odds ratio, 4.1; CI, 0.9-19; P = .08) in a logistic regression analysis, adjusting for pregnancy complications, birth weight, gestational length, and socioeconomic factors. Among children whose mothers were not allergic, the association was much weaker and not significant. Maternal or infant use of antibiotics was not associated with an increased risk of food allergy. Conclusion: The results indicate that in predisposed children cesarean section might increase the risk of development of food allergy, which supports the theory that factors interfering with the colonization process might play a role in the development of food allergy.