About that time Caesar Augustus ordered a census to be taken throughout the Empire.
This was the first census when Quirinius was governor of Syria.
Everyone had to travel to his own ancestral hometown to be accounted for.
So Joseph went from the Galilean town of Nazareth up to Bethlehem in Judah, David's town, for the census. As a descendant of David, he had to go there.
He went with Mary, his fiancŽe, who was pregnant.
While they were there, the time came for her to give birth.