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 [CI] = 13%, 119%) higher if the mother smoked in the same room with the infant, 73% (95% CI = 18%, 157%) higher if the mother smoked when holding the infant, and 95% (95% CI = 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.