• Yu-Fen Li, Bryan Langholz, Muhammad T Salam, and Frank D Gilliland.
• Department of Preventive Medicine, USC Keck School of Medicine, 1540 Alcazar St, CHP 236, Los Angeles, CA 90033, USA.
• Chest. 2005 Apr 1; 127 (4): 1232-41.

ObjectiveTo investigate the associations of maternal and grandmaternal smoking before, during, and after pregnancy with childhood asthma.Design, Setting, And ParticipantsWe conducted a case-control study nested within the Children's Health Study in southern California. The case patients consisted of 338 children with asthma that had been diagnosed in the first 5 years of life, and 570 control subjects were countermatched on in utero exposure to maternal smoking within grade, sex, and community of residence.MeasurementsDetailed maternal and household smoking histories and other asthma risk factor information was obtained by telephone interview.ResultsThe participation rates were 72.3% and 82.5%, respectively, for control subjects and case patients. In utero exposure to maternal smoking was associated with increased risk for asthma diagnosed in the first 5 years of life (odds ratio [OR], 1.5; 95% confidence interval [CI], 1.0 to 2.3), and for persistent asthma (OR, 1.5; 95% CI, 1.0 to 2.3). The associations did not differ in children with early transient asthma compared to those with early persistent asthma. Relative to never-smokers, children whose mothers smoked throughout the pregnancy had an elevated risk of asthma in the first 5 years of life (OR, 1.6; 95% CI, 1.0 to 2.6). Children of mothers who quit smoking prior to the pregnancy showed no increased risk (OR, 0.9; 95% CI, 0.5 to 1.5). We were unable to assess the association of smoking cessation during pregnancy because very few mothers were reported to have done so (15%). Asthma risk did not increase in a monotonic pattern with smoking intensity during pregnancy. Postnatal secondhand smoke exposure was not independently associated with asthma. Grandmaternal smoking during the mother's fetal period was associated with increased asthma risk in her grandchildren (OR, 2.1; 95% CI, 1.4 to 3.2).ConclusionsMaternal and grandmaternal smoking during pregnancy may increase the risk of childhood asthma.

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