Specific parental atopy, sex of child and timing of introduction of 'allergenic' foods

Background: In the Canadian Healthy Infant Longitudinal Development (CHILD) cohort, early introductions of egg, cow9s milk products and peanut were associated with reduced sensitization to these foods at 1 year. We investigated whether these effects differed by specific parental atopy and child sex. Methods: We analyzed feeding patterns in 2284 children in relation to food sensitization at 1 year, stratified by paternal and maternal atopy independently and child sex. Results: In male infants with atopic fathers/non-atopic mothers (n=215), using introduction after 12 months as reference, introduction of cow9s milk products by 6 months reduced sensitization to egg (OR 0.13, 95% CI 0.02,0.91) and peanut (OR 0.08, 95%CI 0.01,0.63); introduction of peanut between 7-12 months reduced sensitization to egg (OR 0.31, 95%CI 0.08,0.94); and introduction of milk between 7-12 months reduced peanut sensitization (OR 0.05, 95%CI 0.01,0.44). Sensitization to any of these 3 foods was reduced by 87% by milk products and 67% by peanut introduction before 12 months. In contrast, among males with atopic mothers/non-atopic fathers (n=110), egg introduction by 6 months reduced the risk of sensitization to any of these 3 foods but no other associations were significant. Female infants with only atopic fathers (n=125) had less milk sensitization if introduced to cow9s milk by 6 months (OR 0.04, 95%CI 0.0,0.69) or between 7-12 months (OR 0.03, 95%CI 0.0,0.77), but among females with only atopic mothers (n=127), no effect of timing of food introduction was evident. Conclusions: Early introduction of allergenic foods was more protective against food sensitization in male infants with atopic fathers.