The Pima infant feeding study: breastfeeding and respiratory infections during the first year of life.

Initial episodes of upper respiratory infection, otitis media, and pneumonia identified from medical records in the first year of life were analysed in relation to feeding practices (ascertained by maternal interview in 1978) among 571 infants born 1960-1977 on the Gila River Reservation. The odds ratio of developing a first episode of upper respiratory infection or otitis media during the first year was less than unity for infants exclusively breastfed for four months compared to exclusively bottlefed infants after logistic regression adjustment for seasonality, birthweight, and adverse social conditions (OR = 0.64). This benefit was evident during the first four months of life (OR = 0.61) and during the second four months (OR = 0.48). However, a significant benefit of early exclusive breastfeeding was no longer demonstrable during months 9-12. Exclusive breastfeeding for four months marginally reduced risk of pneumonia after adjustment for covariates. The data suggest that breastfeeding of infants in early life is associated with reduced risk of respiratory infection.