30 And the angel said to her, “Do not be afraid, Mary, for you have found favor with God. 31 And behold, you will conceive in your womb and bear a son, and you shall call his name Jesus. 32 He will be great and will be called the Son of the Most High. And the Lord God will give to him the throne of his father David, 33 and he will reign over the house of Jacob forever, and of his kingdom there will be no end.”(Gospel of Luke 1:30-35, ESV)
34 And Mary said to the angel, “How will this be, since I am a virgin?”4
35 And the angel answered her, “The Holy Spirit will come upon you, and the power of the Most High will overshadow you; therefore the child to be born will be called holy—the Son of God.”
Birth is an ancient, dangerous, messy and wonderful event, so it's right to celebrate the birth of Jesus. However it's equally important to mark the beginning of the Incarnation when Jesus was miraculously conceived inside Mary. It's interesting that the Annunciation is both pro-life and Trinitarian. It's not often you get all three persons of the Trinity referenced in close proximity and contra the pro-abortion world-view, Jesus is alive inside Mary from the moment of conception.