Behrooz L, et al. - In this case-control study, researchers tested a hypothesis that both maternal prenatal smoking, and postnatal smoke exposure are risk factors for severe bronchiolitis during infancy. They used multivariable logistic regression to assess the independent associations of the two smoking variables with severe bronchiolitis. In either unadjusted or multivariable analyses, maternal prenatal smoking was not found to be related to increased odds of severe bronchiolitis despite its known adverse effects. Postnatal smoke exposure was identified as a consistently strong risk factor. Overall, ongoing efforts to decrease infant exposure to ambient smoke were supported.