Prospective study of breast-feeding in relation to wheeze, atopy, and bronchial hyperresponsiveness in the Avon Longitudinal Study of Parents and Children (ALSPAC)

Background: Breast-feeding clearly protects against early wheezing, but recent data suggest that it might increase later risk of atopic disease and asthma. Objective: We sought to examine the relationship between breast-feeding and later asthma and allergy outcomes by using data from the Avon Longitudinal Study of Parents and Children, a large birth cohort in the United Kingdom. Methods: We used adjusted logistic regression models to evaluate the association between breast-feeding and atopy at age 7 years, bronchial responsiveness to methacholine at age 8 years, and wheeze at ages 3 and 7 1/2 years. Bayesian methods were used to assess the possibility of bias caused by an influence of early wheezing: on the duration of breast-feeding, as well as selection bias. Results: Breast-feeding was protective for wheeze in the first 3 years of life (odds ratio [OR] of 0.80 [95% CI, 0.70-0.90] for >= 6 months relative to never) but not wheeze (OR, 0.98; 95% CI, 0.79-1.22), atopy (OR, 1.12; 95% Cl, 0.92-1.35), or bronchial hyperresponsiveness (OR, 1.07; 95% CI, 0.82-1.40) at ages 7 to 8 years. Bayesian models adjusting for the longer duration of breast-feeding among children with wheezing in early infancy produced virtually identical results. Conclusions: We did not find consistent evidence for either a deleterious effect or a protective effect of breast-feeding on later risk of allergic disease in a large prospective birth cohort of children with objective outcome measures and extensive data on potential confounders and effect modifiers. Neither reverse causation nor loss to follow-up appears to have materially biased our results.