Question: how to unlock the womb in binding of isaac rebirth?
Answer: Womb / Utero Unlocked after beating Mom. Every floor at this point in the game will double any half-heart damage dealt against you to full heart damage (this includes Curse Rooms). The final boss of the Womb/Utero will always be Mom's Heart/It Lives! To unlock Utero, you must beat every possible boss on the Womb floor.