God does not do anything without a purpose!
Luke 2: 12
And this shall be a sign unto you; Ye shall find the babe wrapped in swaddling clothes, lying in a manger.
Our Lord was born in a manger because there was no room for Him in the inn. This account implies that “the inn” should have been the normal place for the birth of our Lord, however because there was no room for Him, he was born in a “manger” A manger means “a long trough from which horses or cattle feed. Not the best of places to be born, but was there a purpose?
I do not claim to know all the reasons, but from verse 12 above one thing is sure “it was a sign”, an identification sign to find the messiah. Read full article from here: