title: Parental and household smoking and the increased risk of bronchitis, bronchiolitis and other lower respiratory infections in infancy: systematic review and meta-analysis.
abstract: BACKGROUND
  Passive smoke exposure increases the risk of lower respiratory infection (LRI) in infants, but the extensive literature on this association has not been systematically reviewed for nearly ten years. The aim of this paper is to provide an updated systematic review and meta-analysis of studies of the association between passive smoking and LRI, and with diagnostic subcategories including bronchiolitis, in infants aged two years and under.
  
  
  METHODS
  We searched MEDLINE and EMBASE (to November 2010), reference lists from publications and abstracts from major conference proceedings to identify all relevant publications. Random effect pooled odds ratios (OR) with 95% confidence intervals (CI) were estimated.
  
  
  RESULTS
  We identified 60 studies suitable for inclusion in the meta-analysis. Smoking by either parent or other household members significantly increased the risk of LRI; odds ratios (OR) were 1.22 (95% CI 1.10 to 1.35) for paternal smoking, 1.62 (95% CI 1.38 to 1.89) if both parents smoked, and 1.54 (95% CI 1.40 to 1.69) for any household member smoking. Pre-natal maternal smoking (OR 1.24, 95% CI 1.11 to 1.38) had a weaker effect than post-natal smoking (OR 1.58, 95% CI 1.45 to 1.73). The strongest effect was on bronchiolitis, where the risk of any household smoking was increased by an OR of 2.51 (95% CI 1.96 to 3.21).
  
  
  CONCLUSIONS
  Passive smoking in the family home is a major influence on the risk of LRI in infants, and especially on bronchiolitis. Risk is particularly strong in relation to post-natal maternal smoking. Strategies to prevent passive smoke exposure in young children are an urgent public and child health priority.
authors.affiliation: UK Centre for Tobacco Control Studies, Division of Epidemiology and Public Health, University of Nottingham, Clinical Sciences Building, Nottingham City Hospital, Nottingham, NG5 1PB, UK. laura.jones@nottingham.ac.uk
authors.forename: Laura L
authors.initials: LL
authors.lastname: Jones
authors.forename: Ahmed
authors.initials: A
authors.lastname: Hashim
authors.forename: Tricia
authors.initials: T
authors.lastname: McKeever
authors.forename: Derek G
authors.initials: DG
authors.lastname: Cook
authors.forename: John
authors.initials: J
authors.lastname: Britton
authors.forename: Jo
authors.initials: J
authors.lastname: Leonardi-Bee
mesh_terms: D001988:Bronchiolitis / Q000209:etiology* / Q000517:prevention & control; D001991:Bronchitis / Q000209:etiology* / Q000517:prevention & control; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D016017:Odds Ratio; D010290:Parents / Q000523:psychology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D012141:Respiratory Tract Infections / Q000209:etiology* / Q000517:prevention & control; D018570:Risk Assessment; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects* / Q000523:psychology; D016540:Smoking Cessation; D000074606:Smoking Prevention; D014028:Tobacco Smoke Pollution / Q000009:adverse effects*
chemical_list: D014028:Tobacco Smoke Pollution