Luther, true to Catholic tradition, wrote on the Virginity of Mary:
 
It is an article of faith that Mary is Mother of the Lord and still a virgin. ... Christ, we believe, came forth from a womb left perfectly intact.
(Weimer's The Works of Luther, English translation by Pelikan, Concordia, St. Louis, v.11, pp. 319-320; v. 6.
p. 510.)