Cigarette Smoking And SIDS

April 1997 British analysis results conclude "maternal smoking doubles the risk of Sudden Infant Death Syndrome." The March 13, 1998 SIDS Alliance Media Advisory summarizes the impact of this study.

The manner in which the press has reported the Fleming Smoking Study and the success of the Back to Sleep Campaign, troubles my wife and I a great deal. The Los Angeles Times gave the Fleming study page one play in its July 26th edition, prompting the response I submitted in a letter to the editor published August 2nd. What follows is the letter, as it was printed by The Times:

Sudden Infant Death Syndrome

Re: "Smoke Makes SIDS Risks Soar, Study Finds"

Recent reports of research studies on sudden infant death syndrome conducted in the United States and Britain hailing the success of the "Back to Sleep" campaigns in reducing the SIDS death rate (placing the baby on its back rather than on its stomach) and linking smoking and other environmental factors to an increased "risk" for SIDS seem to underplay or leave out entirely the most fundamental point about the status of SIDS research efforts:

Researchers don't know what causes this leading killer of babies between two weeks and one year. Because the underlying causes of SIDS remain unknown, all newborn infants are potentially at risk for SIDS.

Babies placed on their backs to sleep still die of SIDS. Babies not exposed to cigarette smoke still die of SIDS. Babies who are breast fed, who have had wonderful prenatal care, who were full term and of normal birth weight, who have parents who have not abused drugs, in short, who have no known risk factors, still die from SIDS.

As the result of the way these research studies are presented, the public may come to view SIDS as somehow "preventable" if we simply alter the child's environment. Of even greater concern to me is the effect of these reports on families who have lost a child to SIDS, and they still number around 500 a year in California, and between 4,500 and 5,000 nationally.

The last thing we need to do to parents who suffer this tragedy is stigmatize or marginalize them. The simple truth is that SIDS can, and does, claim any baby, in spite of parents doing "everything right."

Barry S. Brokaw
SIDS Alliance Board of Directors
Sacramento, CA

A number of people have asked for some commentary on the "British Smoking Study" performed by Professor Peter Fleming in the United Kingdom. It is with some trepidation that I do so, because this is obviously a touchy subject. However, let me try to put this into perspective.

First, as to Professor Fleming's credentials as a researcher, he is outstanding. He and I trained together at the Hospital for Sick Children in Toronto many years ago. Therefore, I have known him for quite some time. He has had excellent research training, and continues to perform the highest quality of research in his own right. For the past several years, he has established probably the best controlled and most accurate study of infant mortality (including SIDS) in the world. Some of the initial work on the effect of prone sleeping and SIDS, as well as the possibility of overheating being a factor, came from his initial work. He told me that he originally did not believe that sleeping position would have an effect on SIDS, but he included questions on this in his initial study "to end discussion on this issue". As we all know, his studies, and others, have suggested that prone sleeping is associated with a higher risk.

I believe it was this work which prompted Professor Fleming to look for other "potentially modifiable risk factors". From a classical medical point of view, this is the strategy which is likely to have the greatest benefit. If one researches potential causes which can not be removed or altered, then it is less likely that the study will have an impact. Thus, Professor Fleming specifically has chosen to look at factors which one could potentially eliminate, such as changing sleeping position or stopping smoking.

In Avon, England, where Professor Fleming performs his studies, prone sleeping has nearly been eliminated. In the absence of prone sleeping, parental cigarette smoking has emerged as the next greatest risk factor for SIDS. His data, which were also presented at the Fourth SIDS International Conference, show a highly significant relationship. Therefore, I believe we must conclude that his findings are real.

What does this mean? Clearly, Professor Fleming is not saying that cigarette smoking is the cause of SIDS. Like with prone sleeping, babies of families where there has been no cigarette smoking continue to die from SIDS, and most babies born into families where one or both parents smoke will not die. So, cigarette smoking is not the cause of SIDS. However, there are two implications of this work:

1) If families can eliminate cigarette smoking during and after pregnancy, the SIDS RISK for that baby is decreased. Therefore, it does give rise to something parents might want to do to try and optimize their chances.

2) Perhaps more important, SIDS risk factors are not CAUSES of SIDS, but they are scientific CLUES to the cause of SIDS. As researchers, we need to think about why cigarette smoking is associated with an increased risk. This line of investigation may lead us to a better understanding of the mechanism of SIDS, and ultimately to learning its cause.

Having personally spoken with Peter Fleming at the Fourth SIDS International Conference about this issue, I know that he also believes that an important implication of this work is that it might lead to an understanding of SIDS. In fact, the "Developmental Physiology Working Party" of the Global Strategy Task Force (which met for 2-days right after the International Conference), set an understanding of the physiologic basis of these risk factors as its highest research priority. Peter Fleming and I were both members of that group.

I think that much of the reaction on this Listserver was due to the media coverage of this research study. I can only say, in my experience of being interviewed by several reporters about SIDS over the years, that reporters are always looking for a "sensational" angle for a story on SIDS. They are not very enthusiastic about printing that SIDS occurs and nothing can be done about it. Therefore, they tend to sensationalize research results, making them sound more significant than they might be. While it would be desirable to change this practice, I don't think we will have much luck at it.

I am not sure where this discussion leaves most of you SIDS parents. I hope it has been a helpful clarification. I would be happy to address additional issues or answer questions (If I can).

Thank you very much.

Tom Keens
Children's Hospital Los Angeles

In response to a question about whether toxins from cigarette smoking could be detected at autopsy in a SIDS baby:

I don't think so. There is one substance, cotinine, which is sometimes analyzed, usually in research studies, to assess the amount of active cigarette smoking one has done. I do not know if this is sensitive enough to be elevated in passive cigarette smoking. Also, this is not a substance which, in and of itself, is toxic or dangerous. Therefore, I expect that very few, if any, Coroners would measure it. Even if they did, the significance of an elevated cotinine would only be that the baby had been exposed to some cigarette smoke. It would say nothing about if or how that might have contributed to the death. Tom Keens
Children's Hospital Los Angeles