Maternal smoking during pregnancy, environmental tobacco smoke exposure and childhood lung function
- Frank D Gilliland,
- Kiros Berhane,
- Rob McConnell,
- W James Gauderman,
- Hita Vora,
- Edward B Rappaport,
- Edward Avol,
- John M Peters
- Department of Preventive Medicine, University of Southern California School of Medicine, Los Angeles, California 90033, USA
- Dr F Gilliland email:
- Received 6 August 1999
- Revision requested 8 November 1999
- Revised 5 January 2000
- Accepted 6 January 2000
BACKGROUND Exposure to environmental tobacco smoke (ETS) during childhood and in utero exposure to maternal smoking are associated with adverse effects on lung growth and development.
METHODS A study was undertaken of the associations between maternal smoking during pregnancy, exposure to ETS, and pulmonary function in 3357 school children residing in 12 Southern California communities. Current and past exposure to household ETS and exposure to maternal smoking in utero were assessed by a self-administered questionnaire completed by parents of 4th, 7th, and 10th grade students in 1993. Standard linear regression techniques were used to estimate the effects of in utero and ETS exposure on lung function, adjusting for age, sex, race, Hispanic ethnicity, height, weight, asthma, personal smoking, and selected household characteristics.
RESULTS In utero exposure to maternal smoking was associated with reduced peak expiratory flow rate (PEFR) (–3.0%, 95% CI –4.4 to –1.4), mean mid expiratory flow (MMEF) (–4.6%, 95% CI –7.0 to –2.3), and forced expiratory flow (FEF75) (–6.2%, 95% CI –9.1 to –3.1), but not forced expiratory volume in one second (FEV1). Adjusting for household ETS exposure did not substantially change these estimates. The reductions in flows associated with in utero exposure did not significantly vary with sex, race, grade, income, parental education, or personal smoking. Exposure to two or more current household smokers was associated with reduced MMEF (–4.1%, 95% CI –7.6 to –0.4) and FEF75 (–4.4%, 95% CI –9.0 to 0.4). Current or past maternal smoking was associated with reductions in PEFR and MMEF; however, after adjustment for in utero exposure, deficits in MMEF and FEF75 associated with all measurements of ETS were substantially reduced and were not statistically significant.
CONCLUSIONS In utero exposure to maternal smoking is independently associated with decreased lung function in children of school age, especially for small airway flows.
This study was supported by the California Air Resources Board (Contract A033-186), the National Institute of Environmental Health Science (Grants 1PO1ESO939581-05 #5P30ES07048-02), the US Environmental Protection Agency (Grant # R826708-01-0), the National Heart, Lung and Blood Institute (Grant # R01 HL/ES61768-01), and the Hastings Foundation.