DO DIFFERENCES IN THE PREVALENCE OF RISK-FACTORS EXPLAIN THE HIGHER MORTALITY FROM SUDDEN-INFANT-DEATH-SYNDROME IN NEW-ZEALAND COMPARED WITH THE UK

Aims. To compare the prevalence of risk factors for the sudden infant death syndrome (SIDS) in New Zealand (SIDS mortality 3.53/1000) with t hat in the South West Thames (SWT) region of the United Kingdom (SIDS mortality 1.36/1000). Methods. The methodology of the study was essent ially identical in New Zealand and SWT. The subjects in both countries were randomly selected from all births in the study regions. The subj ects were randomly allocated an age at which to be interviewed using t he same questionnaire in the two study areas. Obstetric records were a lso examined. Eighteen hundred subjects were selected in New Zealand a nd 700 subjects in SWT. Results. Younger and unmarried mothers were sl ightly more common in New Zealand than in SWT. The prevalence of mater nal smoking, prone sleeping position and infants' sharing of beds with another person were all higher in New Zealand than SWT, thus increasi ng the risk of SIDS (maternal smoking in pregnancy: 31.0% vs 23.8% res pectively, chi(2) = 11.6, p = 0.001; prone sleeping position: 32.9% vs 25.9%, chi(2) = 18.9, p < 0.001; bed sharing: 10.5% vs 6.8%, chi(2) = 6.0, p = 0.14). However, New Zealand infants were breast fed more fre quently and for longer than infants in SWT, which would tend to reduce the risk of SIDS in the New Zealand population. In combination the di fferences in the prevalences of these four risk factors explain only 2 0% of the excess risk of SIDS in New Zealand. Conclusions. The high SI DS mortality rate in New Zealand is not simply explained by a high pre valence of known and modifiable risk. factors for SIDS.