The Blessed Virgin before the birth of Jesus is clearly stated at the Annunciation: Gabriel was sent to "a virgin betrothed to a man, whose name was Mary" (Luke 1:26-35). Afterwards, an angel appeared in a dream to St. Joseph said: "Do not fear to take Mary your wife, for that which is conceived in her is of the Holy Spirit" (Matthew 1:20).

The Virginity of Mary during the birth of Jesus is denied by some theologians because it will support the heresy of Docetism, which says that the body of Jesus was only apparent. However, the Lateran Council (649)), the Council of Trent (1555), and the Catechism of the Catholic Church (1992) profess that the physical virginity of the Blessed Virgin did not end with the birth of Christ: consequently, that Mary gave birth to Jesus painlessly without opening the womb.
The Virginity of Mary during the birth of Jesus is doubted by several Protestants because of the Gospel passage mentioning the "brothers of and sisters" of Jesus (Mark 3:32); the fact that Jesus was Mary's "firstborn son" and that Joseph " had no marital relations with her until she had borne son" (Mathew: 1:25). However, the Greek word adelphoi, used in the Gospel, could mean either "brothers" or " relatives". Furthermore, the legal title firstborn son does not require the existence of siblings: neither the particle until specifies whether after the birth of Jesus Joseph had relationship with Mary.