4 month old baby started rolling on stomach in sleep and is sleeping more comfortably. will he turn head to side? sometimes hes face down in matress.

Two issues: First, I never worry about whether a baby shifts their position at night when they have the physical ability to role. Second, since SIDS is associated with belly sleeping, I don't put them down on their belly for the first year. Yes they can turn their head, and we belly slept babies up until 1992 when the back to sleep movement began. Since then we have seen a 40% decline in SIDS