At the dawn of salvation, it is the birth of a child which is proclaimed as joyful news: ‘I bring you good news of a great joy which will come to all the people; for to you is born this day in the city of David a Savior, who is Christ the Lord’ (Lk. 2:10-11). The source of this ‘great joy’ is the birth of the Savior; but Christmas also reveals the full meaning of every human birth, and the joy which accompanies the birth of the Messiah is thus seen to be the foundation and fulfillment of joy at every child born into the world (cf. Jn. 16:21).
-St. John Paul II, Evangelium Vitae