[Is the increased frequency of sudden infant death caused by changed diagnostic criteria?]

According to the official statistics the incidence of sudden infant death syndrome has more than doubled in Norway during the last 15 years, while the total number of deaths in infants of the same age has changed little during the period. We have reviewed the autopsy protocols from the Department of Pathology, Ullevål Hospital, from 1975 to 1989, and re-examined the histologic lung sections from all children aged from one month to one year who died suddenly and unexpectedly. Of the cases reclassified as sudden infant death syndrome, more than half had been diagnosed as pneumonia during the first five-year period (1975-79). During the last five-year period none of the cases received this diagnosis. We conclude that some of the apparent increase in sudden infant death syndrome recorded in Norway probably reflects a change in diagnostic criteria.