Prenatal Tobacco Smoke Exposure Increases Hospitalizations for Bronchiolitis in Infants

Marcello Lanari; Silvia Vandini; Fulvio Adorni; Federica Prinelli; Simona Di Santo; Michela Silvestri; Massimo Musicco


Respiratory Research. 2015;16(152) 

In This Article


Tobacco smoke exposure (TSE) is a worldwide health problem and a risk factor for children's health particularly for respiratory morbidity during the first years of life.[1–6] TSE during pregnancy, including both passive and active smoke, is also a well known risk factor for several complications of pregnancy and for respiratory disorders of offspring during the first months of life.[1–3]

Moreover, TSE has been associated to a more severe clinical course of bronchiolitis,[4–6] often requiring hospitalization. Viral bronchiolitis is a common lower respiratory tract infection in infants and often requires hospitalization in children younger than 2 years of age. It is characterized by wheezing and mucous plugging, resulting in airway obstruction.[7]

Although the detrimental effects of TSE for children's health are well known, the exposure continues to involve a large amount of infants worldwide: in 2004 about 40 % of the entire pediatric population was exposed to second-hand smoke, with 166,000 of the 5,939,000 respiratory infections and deaths due to this exposure in children younger than 5 years.[8] In several countries, smoke banning laws have been promoted with the aim to reduce the exposure in public places and subsequently protect high risk people, such as pregnant women, newborns and young infants from passive TSE. The introduction of smoke-free legislation in many countries has been related to about a ten percent decrease in preterm births (10.4 %) and in hospital admissions for asthma (10.1 %).[9]

In Italy, the estimated number of smokers is 11.6 million (7.1 million men and 4.5 million women), according to a national report considering the entire Italian population.[10] A comprehensive smoking ban was introduced in 2003 to prohibit smoking in public places, causing a 6.3 % decrease of active smokers in the Italian population.[11]

In an Italian cohort study of infants younger than 2 years hospitalized for acute LRTI,[12] postnatal TSE results to be a significant risk factor for hospitalization.

To our knowledge, few birth cohort studies[13–16] have been carried out that focus on the effect of prenatal TSE via passive and active maternal smoking on the development of lung diseases in childhood, which provide reports that smoke exposure in early life may increase the lung susceptibility to air pollution[16] and that prenatal TSE is related to an earlier onset of asthma. Moreover, no recent birth cohort study has investigated the effect of prenatal and early postnatal TSE on the risk of hospitalization for bronchiolitis during the first year of life.

The aim of the present study is to determine the effects of prenatal passive and active TSE and early postnatal TSE with other risk factors for hospitalization for bronchiolitis in a large cohort of preterm newborns at GA 33 weeks or more and full term newborns.