Review of the epidemiology of sudden infant death syndrome and its relationship to temperature regulation.

Infants dying suddenly and unexpectedly now account for 20% of all infant deaths in England and Wales, and the incidence shows no sign of falling. Recent work relating sudden infant death to a raised environmental temperature and a raised body temperature, implicates fever as a possible contributory cause of death; some infants may be unable to control their febrile response to infection, or to thermoregulate effectively, when well wrapped and heated. Death might then result from apnoea, occurring in a critical sleep state. These ideas have increased the interest in describing the normal practices of parents in caring for the environment of their infants in health and disease, and the effect of their behaviour on the child's temperature. Studies of these areas depend on collecting and interpreting data from young children during their day to day lives, and present a challenge of great relevance to primary care research.