Parental Smoking and Sudden Infant Death Syndrome: A Review of the Evidence

Abstract

This paper reviews evidence relating parental smoking to sudden infant death syndrome (SIDS) risk in their offspring, based on English-language papers covering the period 1966–1996. Twenty-eight prospective and case-control studies provided suitable data. The studies mainly considered maternal smoking during pregnancy, but some studies provided data for maternal smoking before pregnancy, at the time of conception or postnatally, for paternal smoking at various times and/or for postnatal smoking by other household members and day-care providers. Tables were constructed listing unadjusted and covariate-adjusted relative risk estimates for each index of exposure. Associations between SIDS and maternal smoking both during and after pregnancy were consistently observed. Relationships with paternal smoking and with other sources of exposure were also reported in a number of studies. Dose-response relationships were seen for various exposure indices. Several studies found that adjustment for numerous potential confounders very substantially weakened the association between SIDS and parental smoking. Although the possibility of a causal explanation of the associations observed cannot be excluded, the existence of various study weaknesses and the likelihood of residual confounding means that one cannot infer with confidence that parental smoking actually does increase the risk of SIDS.

Review of risk factors for Sudden Infant Death Syndrome

“…A detailed review of all of the major studies of parental smoking and SIDS has been published 239 . The 28 studies reviewed included 15 case–control studies, 8 nested case–control studies (where cases and controls were drawn from within a prospective study), and 5 prospective studies, with a total of 7196 SIDS cases.…”

Changing Conclusions on Secondhand Smoke in a Sudden Infant Death Syndrome Review Funded by the Tobacco Industry

“…The authors concluded that study weaknesses, in particular the failure to control properly for numerous potential confounders, "mean that a causal relationship for parental smoking in SIDS remains unproven." 23 In 1993, Lee charged the United Kingdom Tobacco Manufacturer's Association Advisory Council £12 000 for reviews on SHS and SIDS, childhood cancer, and middle ear disease. 24 In February 1997, PM paid Lee at least $2120 to publish his SIDS article.…”

“…" 27 Because of the general difficulty of "getting tobacco industry funded studies published," 27 Lee 29 ] John Hoskins, whom I know, which has published review papers on ETS-related issues in the past. 27 In 1998, Indoor and Built Environment published the Thornton and Lee article, 23 which acknowledged that "support was provided by several companies of the tobacco industry." (Other articles by Thornton and Lee were also published in Indoor and Built Environment.…”

“…Sullivan's original draft did not include the 1998 SIDS article by Thornton and Lee,23 but the final draft 18 incorporated a descriptive paragraph about the article, stating that much of the association between tobacco exposure and SIDS appeared to be attributable to confounding (Table 3). The article by Thornton and Lee 23 stated that the relative risks from SHS could be reduced with multiple statistical adjustments, which suggests that parental smoking and SIDS are not independently associated.…”

“…21 The first industry-funded SIDS literature review focused only on smoking and SIDS and was written by long-time tobacco industry consultant Peter Lee and his associate Alison Thornton. 23 Lee and Thornton examined 27 studies from 1966 to 1996 and described associations between parental smoking and SIDS risk. The authors concluded that study weaknesses, in particular the failure to control properly for numerous potential confounders, "mean that a causal relationship for parental smoking in SIDS remains unproven."…”