You have a good point, but it is important to remember that the recommendation for “Back to Sleep” i.e. having infants sleep on their back is to help prevent SIDS (sudden infant death syndrome). Since this recommendation came out, the incidence of SIDS has dropped dramatically. If an infant spits up (which is not SIDS), he will usually make some noise to alert his parents. This is why it’s important to follow the AAP recommendation for baby to sleep in the same ROOM as the parents.