Epidemiology of babies dying at different ages from the sudden infant death syndrome.

An analysis of data from the United Kingdom multicentre study of postneonatal mortality has been made to assess whether there are causally distinct groups of babies dying from the Sudden Infant Death Syndrome (SIDS), and to develop explicit risk factor profiles for the subgroups. The 303 SIDS babies in the multicentre study were divided into four subgroups by age at death: weeks 1-7, 8-15, 16-23, and 24 or more weeks. Contrasts between these subgroups with respect to 28 epidemiological characteristics and to pathology findings were investigated. Significant contrasts in the number of previous pregnancies, duration of the 2nd stage of labour, gestational length, family finances and repair of housing were found. Overall, very strong evidence of epidemiological differences was found (chi 2(9) = 29.3, p less than 0.001), and of contrasts in the nature and degree of any acquired terminal disease. It is concluded that there are different causes of SIDS with different distributions according to age at death.