title: Seasonality and the sudden infant death syndrome during 1987-9 and 1991-3 in Australia and Britain.
abstract: OBJECTIVE
  To determine whether seasonality of the sudden infant death syndrome persists now that rates have fallen, mostly after widespread adoption of the "face upwards" sleeping position.
  
  
  METHODS
  Monthly data on the sudden infant death syndrome during 1987-9 were compared for seasonality with those of 1991-3; rates were studied as deaths per 1000 live births.
  
  
  METHODS
  Australia and Britain (England, Wales, and Scotland).
  
  
  METHODS
  Infants under 1 year dying of the syndrome (2401 for Australia and 6630 for Britain).
  
  
  METHODS
  Extent of seasonal variation (amplitude) was established by cosinor analysis; amplitudes for the earlier and later years were compared.
  
  
  RESULTS
  The rate fell in every month, and, though it did so relatively more in winter than summer, seasonality remained a distinctive feature. In the comparison of amplitudes the ratio between the earlier and later years was 1.4 in both Australia and Britain. Some differences between the hemispheres were noted.
  
  
  CONCLUSIONS
  Seasonality of the sudden infant death syndrome remains to be explained and continues to be an important aetiological lead. Studies from other countries are needed.
authors.affiliation: Department of Medicine and Therapeutics, University of Aberdeen Medical School, Foresterhill.
authors.forename: A S
authors.initials: AS
authors.lastname: Douglas
authors.forename: T M
authors.initials: TM
authors.lastname: Allan
authors.forename: P J
authors.initials: PJ
authors.lastname: Helms
mesh_terms: D001315:Australia / Q000453:epidemiology; D006266:Health Education; D006801:Humans; D015994:Incidence; D007223:Infant; D007231:Infant, Newborn; D012189:Retrospective Studies; D012621:Seasons; D012890:Sleep / Q000502:physiology; D013398:Sudden Infant Death / Q000453:epidemiology*; D016683:Supine Position; D006113:United Kingdom / Q000453:epidemiology