Objectives: To investigate the relationship of infant feeding to recurrent wheezing at age 6 years and to assess whether this relationship is altered by a history of wheezing lower respiratory tract illnesses.
Design: Prospective, longitudinal study of healthy infants followed up from birth to 6 years of age.
Setting: Nonselected health maintenance organization population in Tucson, Arizona.
Participants: There were 1246 healthy infants enrolled at birth, 988 of whom had data on both infant feeding and wheezing at age 6 years.
Main outcome measures: Recurrent wheeze (four or more episodes in the past year) was assessed by a questionnaire that was completed by parents when the children were 6 years old. Children were classified by atopic status on the basis of skin prick tests.
Results: Breast-feeding information was collected prospectively, and lower respiratory tract illnesses in the first 3 years of life were diagnosed by the pediatrician. Being breast-fed was associated with lower rates of recurrent wheeze at age 6 years (3.1% vs 9.7%, P < .01) for nonatopic children; this relationship was not significant for atopic children. The relationship of breast-feeding with recurrent wheeze was apparent among nonatopic children both with and without a wheezing lower respiratory tract illness in the first 6 months of life. When potential confounders, including early wheezing lower respiratory tract illness, were included in a multivariate model, nonatopic children who had not been breast-fed had three times the odds of wheezing recurrently (odds ratio, 3.03; confidence interval, 1.06 to 8.69). Eleven percent of recurrent wheeze among nonatopic children could be attributed to not breast-feeding.
Conclusions: Recurrent wheeze at age 6 years is less common among nonatopic children who were breast-fed as infants. This effect is independent of whether the child wheezed with a lower respiratory tract illness in the first 6 months of life.