title: Factors potentiating the risk of sudden infant death syndrome associated with the prone position.
abstract: BACKGROUND
  In several studies the sudden infant death syndrome (SIDS) has been significantly associated with sleeping in the prone position. It is not known how the prone position increases the risk of SIDS.
  
  
  METHODS
  We analyzed data from a case-control study (58 infants with SIDS and 120 control infants) and a prospective cohort study (22 infants with SIDS and 213 control infants) in Tasmania. Interactions were examined in matched analyses with a multiplicative model of interaction.
  
  
  RESULTS
  In the case-control study, SIDS was significantly associated with sleeping in the prone position, as compared with other positions (unadjusted odds ratio, 4.5; 95 percent confidence interval, 2.1 to 9.6). The strength of this association was increased among infants who slept on natural-fiber mattresses (P = 0.05), infants who were swaddled (P = 0.09), infants who slept in heated rooms (P = 0.006), and infants who had had a recent illness (P = 0.02). These variables had no significant effect on infants who did not sleep in the prone position. A history of recent illness was significantly associated with SIDS among infants who slept prone (odds ratio, 5.7; 95 percent confidence interval, 1.8 to 19) but not among infants who slept in other positions (odds ratio, 0.83). In the cohort study, the risk of SIDS was greater among infants who slept prone on natural-fiber mattresses (odds ratio, 6.6; 95 percent confidence interval, 1.3 to 33) than among infants who slept prone on other types of mattresses (odds ratio, 1.8).
  
  
  CONCLUSIONS
  When infants sleep prone, the elevated risk of SIDS is increased by each of four factors: the use of natural-fiber mattresses, swaddling, recent illness, and the use of heating in bedrooms.
authors.affiliation: Menzies Centre for Population Health Research, University of Tasmania, Australia.
authors.forename: A L
authors.initials: AL
authors.lastname: Ponsonby
authors.forename: T
authors.initials: T
authors.lastname: Dwyer
authors.forename: L E
authors.initials: LE
authors.lastname: Gibbons
authors.forename: J A
authors.initials: JA
authors.lastname: Cochrane
authors.forename: Y G
authors.initials: YG
authors.lastname: Wang
mesh_terms: D001512:Bedding and Linens / Q000009:adverse effects; D016022:Case-Control Studies; D016001:Confidence Intervals; D006801:Humans; D015370:Infant Equipment / Q000009:adverse effects; D007231:Infant, Newborn; D016017:Odds Ratio; D016684:Prone Position; D011446:Prospective Studies; D012044:Regression Analysis; D012189:Retrospective Studies; D012307:Risk Factors; D013398:Sudden Infant Death / Q000453:epidemiology / Q000209:etiology*; D013648:Tasmania / Q000453:epidemiology; D013696:Temperature