SIDS in the The News

New study highlights dangers of secondhand smoke for babies

In a recently released study (funded in part by the SIDS Foundation), researchers found significantly higher nicotine concentrations in babies who died of SIDS than in non-SIDS babies .

Previous studies have identified smoking during pregnancy and after birth as two major risk factors for SIDS. However, it has always been difficult to distinguish pre and postnatal exposures. Environmental smoke (ETS) has greater amounts of ammonia, benzene, carbon monoxide, nicotine and carcinogens. Some studies suggest that 20% of women report that they quit or dramatically cut down cigarette use during pregnancy but resumed their habit after their baby was born.

In this study, researchers from the Hospital for Sick Children and at the University of Maryland investigated lung tissue in 44 SIDS cases and 29 non-SIDS cases to determine the levels of both nicotine and cotinine (a major metabolite of nicotine). The lungs are the port of entry for ETS and the concentrations of nicotine and cotinine reflect the burden of ETS.

The study documents that the lungs of infants who died of SIDS had significantly higher levels of nicotine than non-SIDS infants. In comparison with previous studies of nicotine and cotinine levels in adult tissues, the levels of nicotine were higher than the cotinine levels among the infants.

The researchers suggest this may be due to the way in which infants process nicotine and the exclusive absorption of nicotine through their lungs. Nicotine is known to alter the central nervous system neurotransmission and cardiac vascular regulation - which may play a role in the deaths of these infants.

The study also revealed a significant difference in the amount of nicotine found between the SIDS and non-SIDS infants from reported non-smoking environments. Previous studies have documented that families may not volunteer accurate information about cigarette smoking possibly due to guilt, perception of fetal risk and litigious fear.

The authors of the study suggest that the some of the babies reported as living in a non-smoking environment actually lived in a smoking environment. Other factors may have been active/passive smoking during pregnancy and an underreporting of smoking by other household members.

This study does not suggest that smoking causes SIDS or provide a mechanism for how death occurs. It does, however highlight the risks of second-hand smoke (ETS) for infants. It is possible that exposure above a certain level may tip the balance for a vulnerable infant. Researchers also suggest that this lung tissue marker become a standard in all investigations into the sudden and unexpected deaths of infants.