Association between breast feeding and asthma in 6 year old children: findings of a prospective birth cohort study

Objectives To investigate the association between the duration of exclusive breast feeding and the development of asthma related outcomes in children at age 6 years. Design Prospective cohort study, Setting Western Australia. Subjects 2187 children ascertained through antenatal clinics at the major t ertiary obstetric hospital in Perth and followed to age 6 years. Main outcome measures Unconditional logistic regression to model the associ ation between duration of exclusive breast feeding and outcomes related ro asthma or atopy at 6 years of age, allowing for several important confounde rs: sex, gestational age, smoking in the household, and early childcare, Results. After adjustment for confounders, the introduction of milk other t han breast milli before ii months of age was a significant risk factor for all asthma and atopy related outcomes in children aged 6) ears: asthma diag nosed by a doctor (odds ratio 1.25, 95% confidence interval 1.02 to 1.52); wheeze three or more rimes since 1 year bf age (1.41, 1.14 to 1.76); wheeze in the past year (1.31, 1.05 to 1.64); sleep disturbance due to wheeze wit hin the past year (1.42, 1.07 to 1.89), age when doctor diagnosed asthma (h azard ratio 1.22, 1.03 to 1.43); age at first wheeze (1.36, 1.17 to 1.59); and positive skin prick test reaction to at least one common aeroallergen ( 1.30, 1.04 to 1.61). Conclusion A significant reduction in the risk of childhood asthma at age 6 years occurs if exclusive breast feeding is continued for at least the 4 m onths after birth. These findings are important for our understanding of th e cause of childhood asthma and suggest that public health interventions to optimise breast feeding may help to reduce the community burden of childho od asthma and its associated traits.