Are marsupials born in their mother's pouch?

No.

Baby marsupials, or joeys, are born from the mother's birth canal at the base of the tail. Although blind, hairless and completely helpless, the joey (about the size of a bean) clings to its mother's fur, making a long and arduous journey completely by instinct, up to the pouch. Once there, the joey attaches its mouth to a teat, which swells in its mouth to prevent it from being accidentally dislodged.