Background: The aim of the present study was to determine the effect of passive tobacco smoking on growth and infection rate of infants, and to evaluate whether breast-feeding might be protective against harmful effects of cigarette smoke.
Methods: A cross-sectional study on 254 6-7-month-old infants was carried out. A questionnaire was given to mothers; and infants' head circumference, bodyweight, height, and urinary cotinine levels were measured.
Results: Multivariate analysis of factors influencing lower respiratory tract infections showed that smoking mothers increased the rate by 9.1-fold; breast-feeding decreased it by 3.3-fold; formula feeding at birth increased it by a factor of 15.2; another smoker at home increased it by a factor of 40.1. Multivariate analysis of factors influencing upper respiratory tract infections showed that smoking mothers increased the rate by a factor of 23; early formula feeding increased it by a factor of 62; breast-feeding decreased it by a factor of 5; smoking fathers increased it by a factor of 15. Multivariate analysis of factors influencing otitis media found that smoking mothers and fathers increased it by a factor of 9.4 and 6.15, respectively, and breast-feeding decreased it by a factor of 5.4.
Conclusion: Tobacco smoke exposure of infants has negative consequences on growth, otitis media, and upper and lower respiratory tract infections. Breast-feeding promoted the growth of infants who were passively exposed to tobacco smoke and protected them against infections. Smoking should not be permitted in households with infants. When this is impossible, breast-feeding should be promoted to protect the infants against the health hazards of passive smoking.