Prenatal and passive smoke exposure and incidence of asthma and wheeze: systematic review and meta-analysis

Pediatrics. 2012 Apr;129(4):735-44. doi: 10.1542/peds.2011-2196. Epub 2012 Mar 19.


Objectives: Exposure to passive smoke is a common and avoidable risk factor for wheeze and asthma in children. Substantial growth in the prospective cohort study evidence base provides an opportunity to generate new and more detailed estimates of the magnitude of the effect. A systematic review and meta-analysis was conducted to provide estimates of the prospective effect of smoking by parents or household members on the risk of wheeze and asthma at different stages of childhood.

Methods: We systematically searched Medline, Embase, and conference abstracts to identify cohort studies of the incidence of asthma or wheeze in relation to exposure to prenatal or postnatal maternal, paternal, or household smoking in subjects aged up to 18 years old. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were estimated by using random effects model.

Results: We identified 79 prospective studies. Exposure to pre- or postnatal passive smoke exposure was associated with a 30% to 70% increased risk of incident wheezing (strongest effect from postnatal maternal smoking on wheeze in children aged ≤2 years, OR = 1.70, 95% CI = 1.24-2.35, 4 studies) and a 21% to 85% increase in incident asthma (strongest effect from prenatal maternal smoking on asthma in children aged ≤2 years, OR = 1.85, 95% CI = 1.35-2.53, 5 studies).

Conclusions: Building upon previous findings, exposure to passive smoking increases the incidence of wheeze and asthma in children and young people by at least 20%. Preventing parental smoking is crucially important to the prevention of asthma.

Publication types

  • Meta-Analysis
  • Research Support, Non-U.S. Gov't
  • Review
  • Systematic Review

MeSH terms

  • Asthma / epidemiology*
  • Asthma / etiology
  • Female
  • Global Health
  • Humans
  • Incidence
  • Pregnancy
  • Prenatal Exposure Delayed Effects / chemically induced
  • Prenatal Exposure Delayed Effects / epidemiology*
  • Respiratory Sounds / etiology*
  • Risk Assessment*
  • Risk Factors
  • Smoking / adverse effects*
  • Smoking / epidemiology
  • Surveys and Questionnaires
  • Tobacco Smoke Pollution / adverse effects*
  • Tobacco Smoke Pollution / statistics & numerical data


  • Tobacco Smoke Pollution