| The Exposure of Nonsmoking and Smoking Mothers to Environmental Tobacco Smoke during Different Gestational Phases and Fetal Growth Jan Dejmek, Ivo Solansk´y, Katerina Podrazilová, and Radim J. Srám Laboratory of Genetic Ecotoxicology, Regional Institute of Hygiene of Central Bohemia and Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague, Czech Republic Abstract
We studied the impact of maternal exposure to environmental tobacco smoke (ETS) on birth weight (BW) , low birth weight (LBW) , and intrauterine growth retardation (IUGR) according to self-reported maternal smoking habits in a sample of 6,866 singleton births. We obtained data about parental characteristics and maternal active smoking (AS) and passive smoking at delivery via maternal questionnaires and medical records. We used three categories of smoking habits (nonsmokers and those who smoked 1-10 or >10 cigarettes per day) and defined ETS exposure as  5 cigarettes per day smoked by others in the mother's presence. We used multiple regression and logistic regression procedures with adjustment for many associated covariates. We observed a significant reduction of the mean BW in infants of AS mothers. This reduction was only marginal for mothers who stopped smoking after recognizing their pregnancy. ETS exposure in 1,797 of 5,507 nonsmoking mothers reduced the mean BW of their infants by 53 g [95% confidence interval (CI) , 24-82 g]. ETS exposure also significantly reduced BW in babies of AS mothers by 92 g (CI, 21-113 g) compared with BW of ETS-nonexposed AS mothers. The adjusted odds ratio (AOR) of LBW for ETS-exposed AS mothers was two times the LBW risk of ETS-nonexposed AS mothers(2.02 ; CI, 1.11-3.67) ; the AOR of ETS-exposed nonsmoking mothers was 1.51 (CI, 1.02-2.26) . The AOR of IUGR for this group did not differ from unity (1.08 ; CI, 0.82-1.43) . However, ETS exposure increased the AOR of IUGR for AS mothers from 1.64 (CI, 1.06-2.53) to 2.13 (CI, 1.70-2.67) . ETS exposure reduced the BW of infants of nonsmoking mothers and contributed to additional BW reduction in infants of AS mothers. ETS exposure increased the risk of LBW but not that of IUGR in babies of nonsmoking mothers. Key words: active smoking, birth weight, environmental tobacco smoke, fetal growth, IUGR, low birth weight, passive smoking. Environ Health Perspect 110:601-606 (2002) . [Online 26 April 2002] http://ehpnet1.niehs.nih.gov/docs/2002/110p601-606dejmek/ abstract.html Address correspondence to R.J. S(breve) rám, Laboratory of Genetic Ecotoxicology, Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Videnska 1083, 142 20 Prague 4 Czech Republic. Telephone: 420 2 4106 2596. Fax: 420 2 4106 2785. E-mail: sram@biomed.cas.cz We are grateful to the many gynecologists and their staff from the Departments of Obstetrics and Gynecology in the hospitals of Teplice, Duchcov, Prachatice, Vimperk, and Písek. We thank them for their dedication and participation in this study. We also thank our colleagues from the District Institutes of Hygiene in Teplice and Prachatice for their support and collaboration. This work was supported by the grants of the Czech Ministry of Environment (Teplice Program II VaV/340/1/97 and VaV/340/2/00) , U.S. Environmental Protection Agency/U.S. Agency for International Development, and the CEC (PHARE II, EC/HEA-18/CZ) . The work is attributed to the Laboratory of Genetic Ecotoxicology, Regional Institute of Hygiene of Central Bohemia and Institute of Experimental Medicine, Academy of Sciences of the Czech Republic, Prague. Received 18 July 2001 ; accepted 16 October 2001.
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