Until the early 1970s the traditional sleeping position for Dutch infants was not prone. After a much publicised lecture in October 1987 on the possible relation between sleeping prone and cot death, the fairly new habit of placing infants prone is being replaced by more traditional positions. The decrease in the prevalence of the prone sleeping position has been documented in six studies. Since 1987 the incidence of registered cot deaths has decreased from 1.04/1000 live births in 1986 to 0.44 in 1991; the real decrease of sudden unexpected death in infancy, however, is greater.