[A review of recent studies investigating the relationship between sudden infant death syndrome and sleeping...

Recent references (articles and letters) investigating relationship between sudden infant death syndrome (SIDS) and sleeping position are presented. There are many articles which have reported about this association, although repeated investigation or letters by the same researchers were contained. More than 10 epidemiological data in different area or countries were published. The vast majority of reports are retrospective case-control studies, and no study has found prone sleeping to be more common in control cases than in SIDS, although this relation has not always been statistically significant. In addition, a few intervention studies and one cohort study also showed prone sleeping position was associated with an increased risk of SIDS. The recent autopsy cases from Tokyo Medical Examiner's Office showed that most of SIDS infant whose position was recorded were found prone position, and the result was not conflict with reports from Europe and Oceania. Judging from the result of all epidemiological studies, I agree a link between the increased risk of SIDS and prone sleeping position. Health authorities in five developed countries (Netherlands, New Zealand, Australia, the UK and the USA) have advised parents not to place their infant prone to sleep. In these countries except the USA, the reduction of the incidence of SIDS has been reported. In the USA, the prone sleeping has been traditionally received and the incidence of SIDS is lower than in reports from other countries, so all SIDS researchers do not admit the risk of prone sleeping position. The reason of the association between SIDS and prone sleeping position is unknown, but some researchers have thought the mechanism is likelihood of suffocation by rebreathing or/and airway obstruction on particular type of cot, mattress, bedding or clothes. The medical examination system in Japan covers only four regions (the 23 wards in Tokyo, Yokohama, Osaka, Kobe). In almost all other regions, it is difficult to perform the reliable epidemiological study. However, we should collect more Japanese data, as far as possible, before we determine and recommend the "safer" sleeping position of Japanese infants. We need to get further information about not only sleeping position but also other infant care practices.