The main hazard of baby slings is that they can be a suffocation hazard if used incorrectly. (momtricks.com)
Since pillows are a suffocation hazard for young infants and they are not recommended until a child is about two years of age and no longer sleeping in a crib. (howtoadult.com)
These can prove to be a suffocation hazard as well as something to give them leverage to flip themselves over onto their stomach with. (momtricks.com)