Breast feeding and allergic diseases in infants - a prospective birth cohort study

Aims: To investigate the effect of breast feeding on allergic disease in infants up to 2 years of age. Methods: A birth cohort of 4089 infants was followed prospectively in Stockholm, Sweden. Information about various exposures was obtained by parental questionnaires when the infants were 2 months old, and about allergic symptoms and feeding at 1 and 2 years of age. Duration of exclusive and partial breast feeding was assessed separately. Symptom related definitions of various allergic diseases were used. Odds ratios (OR) and 95% confidence intervals (CI) were estimated in a multiple logistic regression model. Adjustments were made for potential confounders. Results: Children exclusively breast fed during four months or more exhibited less asthma (7.7% v 12%, ORadj 0.7, 95% CI 0.5 to 0.8), less atopic dermatitis (24% v 27%, ORadj = 0.8, 95% CI 0.7 to 1.0), and less suspected allergic rhinitis (6.5% v 9%, ORadj = 0.7, 95% CI 0.5 to 1.0) by 2 years of age. There was a significant risk reduction for asthma related to partial breast feeding during six months or more (ORadj = 0.7, 95% CI 0.5 to 0.9). Three or more of five possible allergic disorders-asthma, suspected allergic rhinitis, atopic dermatitis, food allergy related symptoms, and suspected allergic respiratory symptoms after exposure to pets or pollen-were found in 6.5% of the children. Exclusive breast feeding prevented children from having multiple allergic disease (ORadj = 0.7, 95% CI 0.5 to 0.9) during the first two years of life. Conclusion: Exclusive breast feeding seems to have a preventive effect on the early development of allergic disease-that is, asthma, atopic dermatitis, and suspected allergic rhinitis, up to 2 years of age. This protective effect was also evident for multiple allergic disease.