The 'new' risk factors for SIDS: is there an association with the ethnic and place of birth differences in incidence in Victoria, Australia?

Home interviews and assessments of infant development were carried out in a project examining the family environments of four groups of women and their infants with different risks of sudden infant death syndrome (SIDS): a reference group of 200 Australian-born (Anglo-Celtic) women (SIDS incidence, 2.04/1000), 101 women born in Asia (0.97/1000) and 56 women born in Southern Europe (0.58/1000) whose infants have a very low risk of SIDS and 102 women who chose to give birth at home whose infants have a high risk of SIDS (8.9/1000). As these differences are not explained by the classic social and perinatal risk factors, it was possible that they might be attributable to the 'new' risk factors: prone sleeping position, not fully breast feeding, exposure to cigarette smoke and bed sharing. Analysis of the data did not show this expected association: there were no significant differences between the groups in the use of the prone position; although only two Asian-born women smoked, infant exposure to cigarette smoke was similar in the other three groups; choice of infant feeding method did not fit the expected pattern--homebirth infants were fully breast fed almost exclusively while this was so for only about 50% of infants in both low risk groups; more than 50% of homebirth families slept with their infants, but bed sharing was also significantly more common in the Asian-born group than in the reference group.