Parental smoking and infant respiratory infection: How important is not smoking in the same room with the baby?

Objectives. We sought to quantify the effect of good smoking hygiene on infant risk of respiratory tract infection in the first 12 months of life. Methods. A cohort of 4486 infants in Tasmania, Australia, was followed from birth to 12 months of age for hospitalization with respiratory infection. Case ascertainment was 98.2%. Results. Relative to the infants of mothers who smoked postpartum but never in the same room with their infants, risk of hospitalization was 56% (95% confidence interval [Cl]=13%, 119%) higher if the mother smoked in the same room with the infant, 73% (95% Cl=18%, 157%) higher if the mother smoked when holding the infant, and 95% (95% Cl=28%, 298%) higher if the mother smoked while feeding the infant. Conclusions. Parents who smoke should not smoke with their infants present in the same room.