The CPSC recommends putting babies to sleep on their backs, and we fully back this recommendation. According to the CPSC, "Placing babies to sleep on their backs instead of their stomachs has been associated with a dramatic decrease in deaths from Sudden Infant Death Syndrome (SIDS)". With that said, however, there will likely come a time when your baby will turn face down in his or her sleep. That's when having a breathable cover the baby can actually breathe through may be helpful in providing an extra level of protection. A breathable cover can also improve temperature regulation and reduce overheating.