Objective: To examine the hypothesis that bedsharing with an infant is associated with an increased risk of sudden infant death syndrome (SIDS).
Study design: A 1:2, case:control study in Scotland UK, population 5.1 million, including 123 infants who died of SIDS between January 1, 1996 and May 31, 2000, and 263 controls. The main outcome measure was sharing a sleep surface during last sleep.
Results: Sharing a sleep surface was associated with SIDS (multivariate OR 2.89, 95% CI 1.40, 5.97). The largest risk was associated with couch sharing (OR 66.9, 95% CI 2.8, 1597). Of 46 SIDS infants who bedshared during their last sleep, 40 (87%) were found in the parents' bed. Sharing a bed when <11 weeks (OR 10.20, 95% CI 2.99, 34.8) was associated with a greater risk, P = .010, compared with sharing when older (OR 1.07, 95% CI 0.32, 3.56). The association remained if mother did not smoke (OR 8.01, 95% CI 1.20, 53.3) or the infant was breastfed (OR 13.10, 95% CI 1.29, 133).
Conclusions: Bedsharing is associated with an increased risk of SIDS for infants <11 weeks of age. Sharing a couch for sleep should be strongly discouraged at any age.