RISK-FACTORS FOR SUDDEN-INFANT-DEATH-SYNDROME FOLLOWING THE PREVENTION CAMPAIGN IN NEW-ZEALAND - A PROSPECTIVE-STUDY

Objectives. To identify the risk factors for sudden infant death syndr ome (SIDS) following a national campaign to prevent SIDS. Methods. For 2 years (October 1, 1991 through September 30, 1993) data were collec ted by community child health nurses on all infants born in New Zealan d at initial contact and at 2 months. Results. There were 232 SIDS cas es in the postneonatal age group (2.0/1000 live births) and these were compared with 1200 randomly selected control subjects. Information wa s available for 127 cases (54.7%) and 922 (76.8%) of controls.The prev iously identified modifiable risk factors were examined. The prevalenc e of prone sleeping position of the infant was very low (0.7% at initi al contact and 3.0% at 2 months), but was still associated with an inc reased risk of SIDS. In addition, the side sleeping position was also found to have an increased risk of SIDS compared with the supine sleep ing position (at 2 months: adjusted odds ratio (OR) = 6.57; 95% confid ence interval (CI) = 1.71, 25.23). Maternal smoking was found to be th e major risk factor for SIDS. Bed sharing was also associated with an increased risk of SIDS. There was an interaction between maternal smok ing and bed sharing on the risk of SIDS. Compared with infants not exp osed to either bed sharing or maternal smoking, the adjusted OR for in fants of mothers who smoked was 5.01 (95% CI = 2.01, 12.46) for bed sh aring at the initial contact and 5.02 (95% CI = 1.05, 24.05) for bed s haring at 2 months. In this study breastfeeding was not associated wit h a statistically significant reduction in the risk of SIDS. The other risk factors for SIDS identified were: unmarried mother, leaving scho ol at a younger age, young mother, greater number. of previous pregnan cies, late attendance for antenatal care, smoking in pregnancy, male i nfant, Maori ethnicity, low birth weight, and shorter gestation. Concl usions. After adjustment for potential confounders, prone and side sle eping positions, maternal smoking, and the joint exposure to bed shari ng and maternal smoking were associated with statistically significant increased risk of SIDS. A change from the side to the supine sleeping position could result in a substantial reduction in SIDS. Maternal sm oking is common in New Zealand and with the reduction in the prevalenc e of prone sleeping position is now the major risk factor in this coun try. However, smoking behavior has been difficult to change. Bed shari ng is also a major factor but appears only to be a risk to infants of mothers who smoke. Addressing bed sharing among mothers who smoke coul d reduce SIDS by at least one third. Breastfeeding did not appear to o ffer a statistically significant reduction in SIDS risk after adjustme nt of potential confounders, but as breastfeeding rates are comparativ ely good in New Zealand, this result should be interpreted with cautio n as the power of this study to detect a benefit is small.