They put their babies to sleep on their tummies...because that's how babies usually sleep best. I would venture a guess that humans have been putting small babies on their tummies for sleep since the dawn of humankind. Structured "tummy time" recommendations came about because so many babies were delayed in reaching their developmental milestones, directly related to the Back-To-Sleep campaign. Babies really are delayed because of BTS. It's not a bullsh1t diagnosis.