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Chronic carbon monoxide poisoning as a major contributing factor in the sudden infant death syndrome.

Sir .—Many causes of sudden infant death syndrome (SIDS) have been proposed but no one cause or combination of causes has been established. 1 A current hypothesis is that SIDS may be the result of a breakdown in the integration of the complex regulatory systems to maintain life. 2 One stress factor that has not been investigated adequately is exposure to carbon monoxide and its subsequent effects on respiratory control in infants. Carbon monoxide is one of the by-products of the incomplete combustion of organic materials that most commonly originates from cigarette smoke, inadequately vented heating systems, and automobile exhaust. Carbon monoxide binds with hemoglobin with an affinity 250 times greater than that of oxygen. 3 Some of the pathologic abnormalities of SIDS and carbon monoxide poisoning are similar to and consistent with chronic hypoxia. 3,4 A high association of mothers who smoke cigarettes during pregnancy and after delivery has