The Placenta is a passive item added in The Binding of Isaac:Rebirth.
Blood appears around Isaac's mouth, similar to the visual effect of Jesus Juice .
Increases maximum health by one heart container. Also grants passive health regeneration. Usually it regenerates half of heart every minute (bound to timer, that can be seen by pressing Tab), but has some abuse preventing limitations (for example, regeneration timer will not reset if there are not enemies in room).