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Cigarette smoking and sudden infant death syndrome: some salient points in the debate

Maternal smoking has been discussed as a potential risk factor for sudden infant death syndrome (SIDS) for at least three decades. The earliest study I have found is a case-control study from Ontario, referring to the period 1959-1962 ( I ) , in which an odds ratio (OR) of 2.5 for smokers versus non-smokers was reported. In a cohort study from Oakland in the early 1960s, Lewak et al. reported that maternal smoking doubled the risk of SIDS; from 2.3 per 1000 to 4.6 per 1000 live births (2). The literature on SIDS and smoking is scant. Two recent overviews give the impression that only a dozen articles on this subject have been published during the last two decades (3, 4). However, a MEDLINE search resulted in 43 articles between 1967 and February 1992. This is probably an underestimation of the number of articles dealing with SIDS and smoking habits, due to the fact that smoking is rarely the main focus of the study and results can be reported without being mentioned in abstracts or as key words. The overall impression given by the available literature is that maternal cigarette smoking is associated with SIDS with ORs ranging between 1.5 and 5. In Table 1 the results of some of the studies are presented. The three studies in Table 1 where smokers are compared with non-smokers have all reported ORs of approximately 2 (2, 5, 6). In the studies of different levels of