Thanks for the interesting link, but I really don't get why Catholics insist that it's important that Mary's hymen was preserved during the act of giving birth. The hymen is merely a tissue that is sometimes torn during vigorous exercise before a woman experiences sexual intercourse, and that sometimes is so tough that it's advisable for a doctor to break it before intercourse is attempted. It has absolutely nothing to do with moral choices. Clearly there would be nothing immoral about its being broken during the birth of the immaculately conceived Savior.
What is with the obsession with technical virginity? Isn't virginity the result of choices about sex, having nothing to do with a divine birth?