Purpose: The aim of this paper is to compare international trends in sudden infant death syndrome (SIDS) and postneonatal mortality (PNM) since the introduction of SIDS risk reduction and safe sleep campaigns, offer possible explanations for differences, and to provide recommendations to improve consistency in classifying and reporting sudden unexpected deaths in infancy (SUDI) internationally. Methods: SIDS and postneonatal mortality rates were obtained for 15 countries from 1990 through the year for which most recent data were available. Results: SIDS rates have declined in all countries, with reductions well over 50% for most countries. These declines are attributed to SIDS risk reduction campaigns, which achieved success primarily in reducing rates of prone sleeping among infants. The largest declines generally occurred in the first few years after initiation of national campaigns, and there are concerning indications that these rates have reached plateaus in many countries. Conclusions and Recommendations: Diagnostic accuracy is essential to monitor and compare trends in SIDS and other sudden unexpected infant deaths. This requires establishing sudden infant death definitions and diagnostic categories that are agreed upon widely. National and local campaigns need to be reenergized to continue the early successes made in reducing SIDS incidence. Finally, data collection needs to be easy to access and this would best be accomplished by national vital statistics agencies posting data in a uniform way on their websites.
Keywords: Sudden infant death syndrome (SIDS), sudden unexpected death in infancy (SUDI), infant mortality, trends, risk factors, classification