Spock advocated that infants should not be placed on their back when sleeping, commenting in his 1958 edition that "if [an infant] vomits, he's more likely to choke on the vomitus." This advice was extremely influential on health-care providers, with nearly unanimous support through to the 1990s.[9] Later empirical studies, however, found that there is a significantly increased risk of sudden infant death syndrome (SIDS) associated with infants sleeping on their abdomens. Advocates of evidence-based medicine have used this as an example of the importance of basing health-care recommendations on statistical evidence, with one researcher estimating that as many as 50,000 infant deaths in Europe, Australia, and the US could have been prevented had this advice been altered by 1970, when such evidence became available.[10]