Luke 2:5 in the World English Bible
to enroll himself with Mary, who was pledged to be married to him as wife, being pregnant.
Context
4 And Joseph also went up from Galilee, out of the city of Nazareth, into Judæa, unto the city of David, which is called Bethlehem; (because he was of the house and lineage of David:)
5 To be taxed with Mary his espoused wife, being great with child.
6 And so it was, that, while they were there, the days were accomplished that she should be delivered.