Baby Lost Blue is a Co-op Baby in The Binding of Isaac.

Co-op players turn into this baby upon death if playing as ???. It shoots very weak tears, but cannnot take damage. It cannot fly over pits either. Upon defeating the floor's boss, the co-op player reverts to its normal form.

This baby has no unlock method.

This baby was added in Repentance.

• Check out the full list of babies on the external Isaac Wiki.