Environment of infants during sleep and risk of the sudden infant death syndrome: results of 1993-5 case-control study for confidential inquiry into stillbirths and deaths in infancy

Abstract

Objective : To investigate the role of sleeping arrangements as risk factors for the sudden infant death syndrome after a national risk reduction campaign. Design : Two year population based case-control study. Parental interviews were conducted for each infant who died and for four controls matched for age and date of interview. Setting : Three regions in England with a total population of 17 million people. Subjects : 195 babies who died and 780 matched controls. Results : Prone and side sleeping positions both carried increased risks of death compared with supine when adjusted for maternal age, parity, gestation, birth weight, exposure to smoke, and other relevant factors in the sleeping environment (multivariate odds ratio = 9.00 (95% confidence interval 2.84 to 28.47) and 1.84 (1.02 to 3.31), respectively). The higher incidence of side rather than prone sleeping led to a higher population attributable risk (side 18.4%, prone 14.2%). More of the infants who died were found with bed covers over their heads (21.58; 6.21 to 74.99). The use of a dummy had an apparent protective effect (0.38; 0.21 to 0.70). Bed sharing for the whole night was a significant risk factor for infants whose mothers smoked (9.25; 2.31 to 34.02). No protective effect of breast feeding could be identified on multivariate analysis. Conclusions : This study confirms the importance of certain risk factors for the sudden infant death syndrome and identifies others—for example, covers over the head, side sleeping position—which may be amenable to change by educating and informing parents and health care professionals. Key messages: This large case-control study is the first after the national campaign to reduce the risk of the syndrome The risk of sudden infant death is increased by prone or side sleeping position; loose bedding (particularly duvets), which can slip over the baby's head; and bed sharing by mothers who smoke The risk may be reduced by supine sleeping position; placing the baby with feet at the foot of the cot (“feet to foot”); ensuring that bedding is securely tucked in; and avoiding the use of duvets