In Catholic dogmatic theology, not only was Mary a perpetual virgin in the sense that she never engaged in sexual intercourse, even after the birth of Jesus, but was a perpetual virgin physically, too. As Catholic theologian Ludwig Ott wrote:
2. Virginity During the Birth of Jesus
Mary bore her Son without any violation of her virginal integrity. (De fide on the ground of the general promulgation of doctrine.)
The dogma merely asserts the fact of the continuance of Mary’s physical virginity without determining more closely how this is to be physiologically explained. In general the Fathers and the Schoolmen conceived it as non-injury to the hymen, and accordingly taught that Mary gave birth in miraculous fashion without opening of the womb and injury to the hymen, and consequently also without pains (cf. S. th. III 28, 2). (Ott, L. (1957). Fundamentals of Catholic dogma (p. 205). St. Louis: B. Herder Book Company.)
This aspect of the perpetual virginity of Mary seems to be explicitly contradicted by the testimony of Scripture. In Luke 2:21-24 (RSV) we read the following:
And at the end of eight days, when he was circumcised, he was called Jesus, the name given by the angel before he was conceived in the womb. And when the time came for their purification according to the law of Moses, they brought him up to Jerusalem to present him to the Lord (as it is written in the law of the Lord, "Every male that opens the womb shall be called holy to the Lord") and to offer a sacrifice according to what is said in the law of the Lord, "a pair of turtledoves, or two young pigeons."
As Eric Svendsen noted about this pericope and v. 23’s reference to the phrase “opens the womb”:
The Roman Catholic teaching of Mary’s virginity during birth (in partu) (i.e., without rupture of the hymen) seems to be negated by Luke’s phrase in v. 22 that Jesus “opened the womb” (διανοῖγον μήτραν). The sacrifice made in vv.21-24 presupposes a normal birth process for Jesus, and many Catholic scholars note that it is unlikely that Luke would have employed this phrase if he had known of this Marian tradition. (Eric D. Svendsen, Who is My Mother? The Role and Status of the Mother of Jesus in the New Testament and Roman Catholicism [Amityville, N.Y.: Calvary Press, 2001], 143)