Initiatives such as the "Back to Sleep" campaign and emphasis on the risks of parental smoking, bed sharing, and intoxication are believed to have markedly reduce the incidence of Sudden Infant Death Syndrome (SIDS; cot death) since the early 1990s. SIDS is one of the leading causes of death in infants, it is defined as:
"sudden unexpected death of an infant less than one year of age, with onset of the fatal episode apparently occurring during sleep, that remains unexplained after a thorough investigation, including performance of a complete autopsy and review of the circumstances of death and the clinical history."The incidence of SIDS has continued to decline into the 21st century - and this should be a good thing. Unfortunately there is convincing evidence from studies in the US that the more recent decline in SIDS is due to changing patterns in the reporting of cause of death and thus does not reflect a real improvement in overall infant mortality rates.
If we look at the graph from Shapiro-Mendoza et al we can see that while rates of SIDS have decreased since the mid-nineties, there is a corresponding increase in the rate of other causes of sudden, unexpected infant death such as accidental suffocation and asphyxia, or simply 'cause unknown/unspecified'. (The fall in the early-nineties does not show this pattern and presumably represents a true decrease in cases of SIDS).
Sadly, our success in preventing SIDS since the mid-nineties looks as though it is actually the result of changing diagnostic practices, perhaps a decreased willingness to assign a diagnosis of SIDS to potential infanticide (hence 'cause unknown/unspecified'), or due to more thorough investigation of the cause of death (and thus accidental suffocation and asphyxia). But what it does highlight is the need for caution in interpreting incidence data over time (cf. autism).