90 ©2006 Blackwell Publishing Ltd. Paediatric and Perinatal Epidemiology, 20, 90–99 PPEPaediatric and Perinatal Epidemiology0269-5022Blackwell Publishing Ltd, 2005 20062029099Original ArticleSmoking, snuff use and pregnancy outcomesK. Steyn et al. Correspondence: Dr Krisela Steyn, Chronic Diseases of Lifestyle Unit, Medical Research Council, PO Box 19070, Tygerberg 7505, South Africa. E-mail: krisela.steyn@mrc.ac.za The influence of maternal cigarette smoking, snuff use and passive smoking on pregnancy outcomes: the Birth To Ten Study Krisela Steyn a , Thea de Wet b , Yussuf Saloojee c , Hannelie Nel d and Derek Yach e a Chronic Diseases of Lifestyle Unit of the Medical Research Council, Parowvallei, b Department of Anthropology and Developmental Studies, University of Johannesburg, c National Council Against Smoking, Johannesburg, d Department of Logistics, University of Stellenbosch, Stellenbosch, South Africa, and e Department of Public Health, Yale University School of Medicine, Newheven, CT, USA Summary Steyn K, de Wet T, Saloojee Y, Nel H, Yach D. The influence of maternal cigarette smoking, snuff use and passive smoking on pregnancy outcomes: the Birth To Ten Study. Paediatric and Perinatal Epidemiology 2006; 20: 90–99. This article describes the patterns and effects of maternal snuff use, cigarette smoking and exposure to environmental tobacco smoke during pregnancy on birthweight and gestational age, in women living in Johannesburg and Soweto in 1990. A cohort of 1593 women with singleton live births provided information about their own and household members’ usage of tobacco products during pregnancy. The women completed a ques- tionnaire while attending antenatal services. Data on gestational age and birthweight were obtained from birth records. Women who smoked cigarettes or used snuff during pregnancy accounted for 6.1% and 7.5% of the study population respectively. The mean birthweight of non-tobacco users was 3148 g [95% CI 3123, 3173] and that of the smokers 2982 g [95% CI 2875, 3090], resulting in a significantly lower mean birthweight of 165 g for babies of smoking mothers (P = 0.005). In contrast, women using snuff gave birth to infants with a mean birthweight of 3118 g [95% CI 3043, 3192], which is a non-significant (P = 0.52) decrease (29.4 g) in their infants’ birthweights compared with those not using tobacco. A linear regression analysis identified short gestational age, female infant, a mother without hypertension during pregnancy, coloured (mixed racial ancestry), and Asian infants compared with black infants, lower parity, less than 12 years of education and smoking cigarettes as significant predictors of low birthweight, while the use of snuff during pregnancy was not associated with low birthweight. The snuff users, however, had a significant shorter gestational age than the other two groups of women. The birthweight reduction adjusted for possible confounders was 137 g [95% CI 26.6, 247.3 (P = 0.015)] for cigarette smokers and 17.1 g [95% CI -69.5, -102.7, P = 0.69] for snuff users respectively, compared with the birth- weight of non-tobacco users. Among women who did not smoke cigarettes or use snuff, exposure to environmental tobacco smoke did not result in significant effects on the birthweight of their infants. In conclusion, infants of cigarette smokers had significantly lower birthweights than those of non-tobacco users or snuff users who are exposed to nicotine during preg- nancy. Passive smoking did not affect birthweight significantly in this population. Keywords: maternal cigarette smoking, snuff use, environmental tobacco smoke, pregnancy outcomes. Introduction Maternal cigarette smoking during pregnancy leads to many complications; the most common being retarda- tion of intrauterine growth resulting in a reduced fetal weight and size. 1,2 The health effects of smokeless tobacco during pregnancy have received far less atten- tion with limited publications describing this prac- tice. 3,4 Characterisation of this latter association is