Maternal cigarette smoking, breast-feeding, and respiratory tract infections in infancy. A population-based cohort study.

This population-based study comprised 192 mothers and their infants; 58 mothers were smokers and 134 non-smokers. At the 18-month infant check-up at the child health clinic, mothers were questioned about the length of the breast-feeding period, both exclusively breast-feeding and overall breast-feeding time. The numbers of antibiotic-treated respiratory tract infections (RTIs) during the first year of life were noted during a scrutiny of records at the district physician's surgery and child health clinic of the Health Centre, and at the paediatric and ENT departments of the Central Hospital. We were unable to find any connection between the duration of breast-feeding and the number of antibiotic-treated RTIs in the infants. This applied to both exclusively breast-feeding period and overall breast-feeding period. Further, it was shown that infants of smokers were affected by RTIs more often than those of non-smokers, the incidence figures being 1.16 vs. 0.76 antibiotic courses per infant and year, respectively. Moreover, infants of smokers were breast-fed for a shorter period than those of non-smokers, the mean values being 3.3 vs. 4.3 months, respectively, for the period of exclusively breast-feeding, and 5.0 vs. 7.2 months, respectively, for the overall breast-feeding period.