Objective: Self-reported maternal smoking is associated with a dose-related-increase in the risk of sudden infant death syndrome (SIDS). The aim of this study was to measure objectively whether victims of SIDS are more exposed to tobacco smoke before death than infants who die unexpectedly of other causes.
Design: Continine levels in pericardial fluid were used as an indicator of exposure. Levels > 5 ng/mL indicated significant exposure, and levels > 20 ng/mL indicated heavy exposure. Samples were obtained from all sudden deaths in children < 7 years of age that occurred from 1990 through 1993 in southeastern Norway. Twenty four infants died of SIDS, 12 infants of infections, and 9 of accidents (median age 4.5, 5, and 35 months, respectively).
Results: Compared with the age-matched infectious deaths, a significantly higher proportion of victims of SIDS had been significantly (92% vs 67%) or heavily exposed (25% vs 0%) to nicotine, (P < .05). Median cotinine levels in infants with SIDS, 15.8 ng/mL, were significantly higher than in infants who had infectious deaths 7.1 ng/mL (P < .003) but were comparable to those of accident victims (12.9 ng/mL, not significant).
Conclusions: Victims of SIDS are more often and more heavily exposed to tobacco smoke doses before death than are infants who have sudden infectious deaths. Accidental death in infancy and childhood is often associated with a significant exposure to nicotine.