The introduction of allergenic foods and the development of reported wheezing and eczema in childhood: The generation R study
Objective: To examine whether the timing of introduction of the allergenic foods cow's milk, hen's egg, peanuts, tree nuts, soy, and gluten is associated with eczema and wheezing in children 4 years of age or younger. Design: Population-based prospective cohort study from fetal life until young adulthood. Setting: Rotterdam, the Netherlands, from April 2002 through January 2006. Participants: A total of 6905 preschool children participating in the Generation R study. Main Exposure: Timing of introduction of cow's milk, hen's egg, peanuts, tree nuts, soy, and gluten collected by questionnaires at 6 and 12 months of age. Main Outcome Measures: Information on the outcomes eczema and wheezing were obtained by questions from the age-adapted version of the "International Study of Asthma and Allergies in Childhood" core questionnaire and questionnaire data on parentally reported physician diagnosis for eczema. Results: Of 6905 children, wheezing was reported in 31% at age 2 years and in 14% at ages 3 and 4 years. Eczema was reported in 38%, 20%, and 18% of children at the ages of 2, 3, and 4 years, respectively. The introduction of cow's milk, hen's egg, peanuts, tree nuts, soy, and gluten before the age of 6 months was not significantly associated with eczema or wheezing at any age after adjustment for potential confounders (P>.10 for all comparisons). The results did not alter after stratification according to the child's history of cow's milk allergy and parental history of atopy. Conclusion: This study does not support the recommendation for delayed introduction of allergenic foods after age 6 months for the prevention of eczema and wheezing.