But as the Conception itself transcends the order of nature, so the birth of our Lord presents to our contemplation nothing but what is divine.
Besides, what is admirable beyond the power of thoughts or words to express, He is born of His Mother without any diminution of her maternal virginity, just as He afterwards went forth from the sepulchre while it was closed and sealed, and entered the room in which His disciples were assembled, the doors being shut; or not to depart from every-day examples, just as the rays of the sun penetrate without breaking or injuring in the least the solid substance of glass, so after a like but more exalted manner did Jesus Christ come forth from His mother's womb without injury to her maternal virginity. ................ To Eve it was said: In sorrow shalt thou bring forth children. Mary was exempt from this law, for preserving her virginal integrity inviolate she brought forth Jesus the Son of God without experiencing, as we have already said, any sense of pain.
CATECHISM OF THE COUNCIL OF TRENT
PART 1: THE CREED
Article III