Table 1

Summary of effects of parental smoking on the respiratory health of children

OutcomeEither parent OR (95% CI) Mother OR (95% CI) Father only OR (95% CI) Both parents OR (95% CI)
Lower respiratory illnesses (LRI) at age 0–2
All studies1.57 (1.42 to 1.74) [27]1.72 (1.55 to 1.91) [27]1.29 (1.16 to 1.44) [16]
 Community studies of wheeze1.55 (1.16 to 2.08) [5]2.08 (1.59 to 2.71) [7]
 Community studies of LRI,  bronchitis and/or pneumonia1.54 (1.31 to 1.80) [11]1.57 (1.33 to 1.86) [7]
 Hospital admission for LRI,  bronchitis, bronchiolitis or  pneumonia1.71 (1.21 to 2.40) [8]1.53 (1.25 to 1.86) [9]1.32 (0.87 to 2.00) [6]
Prevalence rates at age 5–16
Wheeze1.24 (1.17 to 1.31) [30]1.28 (1.19 to 1.38) [18]1.14 (1.06 to 1.23) [10]1.47 (1.14 to 1.90) [11]
 Cough1.40 (1.27 to 1.53) [30]1.40 (1.20 to 1.64) [14]1.21 (1.09 to 1.34) [9]1.67 (1.48 to 1.89) [16]
 Phlegm1.35 (1.13 to 1.62) [6]1.46 (1.04 to 2.05) [5]
 Breathlessness1.31 (1.08 to 1.59) [6]
 Asthma (cross sectional studies)1.21 (1.10 to 1.34) [21]1.36 (1.20 to 1.55) [11]1.07 (0.92 to 1.24) [9]1.50 (1.29 to 1.73) [8]
 Asthma (case-control studies)1.37 (1.15 to 1.64) [14]
 Bronchial reactivity1.291-152 (1.10 to 1.50) [10]
 Skin prick positivity0.871-150 (0.64 to 1.24) [8]
Incidence of asthma
Under age 61.311-151 (1.22 to 1.41) [4]
 Over age 61.131-151 (1.04 to 1.22) [4]
Middle ear disease
Acute otitis mediaRange 1.0 to 1.6 [8]
 Recurrent otitis media1.48 (1.08 to 2.04) [7]
 Middle ear effusion1.381-151 (1.23 to 1.55) [4]
 Referral for glue ear1.211-151 (0.95 to 1.53) [7]
 Sudden infant death1-154 2.13 (1.86 to 2.43) [18]

  • ↵1-150 Results relate to maternal smoking during pregnancy or exposure to environmental tobacco smoke (ETS) in infancy. Data for ETS exposure during later childhood are too heterogeneous for meta-analysis.

  • ↵1-151 Based on fixed effects estimate.

  • ↵1-152 Relates largely, but not entirely to maternal smoking.

  • ↵1-154 Estimate and confidence limits differ from those in reference 2 due to exclusion of the study by Bulterys et al(see Erratum at end of this paper).

  • Numbers in square brackets are numbers of studies on which pooled odds ratios based.

  • Source of data: references 1–7.