The contribution of changes in the prevalence of prone sleeping position to the decline in sudden infant death syndrome in Tasmania.
OBJECTIVE
To determine the independent contribution of changes in infant sleep position to the recent decline in sudden infant death syndrome (SIDS) rate in Tasmania.


METHODS
(1) A comparison of the whole population incidence of SIDS before and after an intervention to reduce the prevalence of prone sleeping position. (2) A within-cohort analysis of the contribution of sleep position and other exposures to the decline in SIDS after the intervention.


METHODS
Tasmania, Australia.


METHODS
(1) All SIDS cases from 1975 through 1992. (2) A sample of one in five infants born in Tasmania who at perinatal assessment were scored to be at higher risk for SIDS since January 1988. Of 5534 infants included in the study, 39 later died of SIDS.


METHODS
Multiple public health activities to reduce the prevalence of the prone infant sleeping position in Tasmania and verbal information on the association between prone position and SIDS to cohort participants from May 1, 1991.


METHODS
Sudden infant death syndrome incidence.


RESULTS
The Tasmanian SIDS rate decreased (P < .01) from 3.8 (95% confidence interval [CI], 3.5 to 4.2) deaths per 1000 live births from 1975 through 1990 to a rate of 1.5 (95% CI, 0.9 to 2.2) deaths per 1000 live births in 1991 through 1992. The SIDS mortality rate in the cohort by period of birth was 7.6 (95% CI, 4.9 to 10.3) deaths per 1000 live births for those born from May 1, 1988, through April 30, 1991, and 4.1 (95% CI, 1.3 to 7.0) deaths per 1000 infants for those born from May 1, 1991, through October 31, 1992. The prevalence of usual prone sleeping position at 1 month of age was 29.9% and 4.3% in these two cohorts, respectively (adjusted odds ratio, 0.11; 95% CI, 0.08 to 0.13). Logistic regression demonstrated that 70% of the SIDS rate reduction in the cohort could be accounted for by the decreased prevalence of the prone sleeping position. Other factors examined individually contributed to less than 10% of the SIDS rate reduction.


CONCLUSIONS
The major contributing factor to the recent SIDS rate decline in Tasmania has been the reduction in the proportion of infants usually sleeping prone.
Dwyer
T
T
Menzies Centre for Population Health Research, University of Tasmania, Hobart, Australia.
Ponsonby
A L
AL
Blizzard
L
L
Newman
N M
NM
Cochrane
J A
JA
D015331:Cohort Studies; D006801:Humans; D015994:Incidence; D007223:Infant; D007226:Infant Mortality; D007231:Infant, Newborn; D016015:Logistic Models; D011187:Posture; D015995:Prevalence; D016684:Prone Position; D012307:Risk Factors; D012890:Sleep; D013398:Sudden Infant Death / Q000453:epidemiology*; D016683:Supine Position; D013648:Tasmania / Q000453:epidemiology