Seasonal differences in risk factors for sudden infant death syndrome. The New Zealand Cot Death Study Group.
The aim of this study was to explore whether the risk of sudden infant death syndrome (SIDS) associated with prone sleeping position and other risk factors varies with season. The study was a large nation-wide case-control study, which compared 485 cases with 1800 controls. Parents of 393 (81.0%) cases and 1591 (88.4%) controls were interviewed. Obstetric records were also examined. Infants dying in winter were older and had lower birthweights than those dying in summer. The increased risk of SIDS associated with prone sleeping position was greater in winter than in summer. In contrast, the increased risk of SIDS associated with excess thermal insulation and bed sharing was less in winter than in summer. Prone sleeping position accounts for about half of the difference between the mortality rate in summer and that in winter. This suggests that some factor related to season modifies the effect of prone sleeping position.
Mitchell
E A
EA
Department of Paediatrics, University of Auckland, New Zealand. e.mitchell@auckland.ac.nz
Clements
M
M
Williams
S M
SM
Stewart
A W
AW
Cheng
A
A
Ford
R P
RP
D017677:Age Distribution; D000367:Age Factors; D000704:Analysis of Variance; D001724:Birth Weight; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D009520:New Zealand / Q000453:epidemiology; D016684:Prone Position; D012307:Risk Factors; D012621:Seasons; D012890:Sleep; D013398:Sudden Infant Death / Q000209:etiology*; D011795:Surveys and Questionnaires; D013997:Time Factors