The consequences of the annunciation made to Mary by the angel Gabriel more than 2,000 years ago are almost impossible to exaggerate.

“Never in human history did so much depend, as it did then, upon the consent of one human creature,” writes Pope John Paul II in Tertio Millennio Adveniente (Advent of the Third Millennium, No. 2).

This world-changing event is celebrated on the solemnity of the Annunciation (a day later this year because March 25 falls on a Sunday in Lent). There is a movement to make that day the “Day of the Unborn Child,” with a weeklong pro-life remembrance. We think it's an excellent idea.

The day Mary said Yes to God is rife with pro-life significance.

It comes at time when the world has given a great No to God's plan for us. Where mary said Yes to being the mother of God our culture often says No to motherhood. Where her Yes led to the incarnation of Christ and to the new culture of Christianity our Nos have led to the demolition of that culture and the creation of what the Pope calls a “culture of death”

The day of the Annunciation and the week following it also occasioned the Gospels to give evidence for the humanity of the unborn. And not just the unborn — they show the humanity of the embryo as well.

Immediately after Mary was invited to be the mother of the Messiah, and consented, the Gospel tells us that she “went in haste” to a town in the hill country of Judea to visit her cousin Elizabeth. Researchers identify the place as a little village called Ain Karim, about five miles west of Jerusalem. Even if she went on foot, the journey would have taken no more than a week. Yet upon seeing Mary, her cousin said, “How does it happen that the mother of my Lord should come to me?”

The pro-life implications of this greeting are tremendous. First, Mary is addressed as “mother” — not somebody who might become a mother later on, if the embryo becomes a fetus and the fetus implants and the implanted fetus is “carried to term.” Days after conception, she is a mother.

And the tiny embryo in her womb is called “my Lord” — a title never given to a thing, only to a person. For Elizabeth to address Mary as the Mother of her Lord is a biblical confirmation of the personhood of the embryo, from the first days of conception.

In our time embryos are created and destroyed with no regard for their humanity. Practices like in-vitro fertilization can seem a great boon to infertile couples — but the practice inevitably leads to the destruction of embryos.

Other embryos are used as research specimens in medical programs promoted by celebrities like Christopher Reeve and Michael J. Fox, who argue that embryos should be harvested to help cure disease. Their arguments can sound compelling. But it is important to remember that Our Lord himself was an embryo once; it was precisely as an embryo that he was first called “Lord.” This gives that age a new significance.

Last, a greater celebration of the Annunciation would help fulfill the program of the new evangelization the Holy Father laid out in his 1999 postsynodal apostolic exhortation Ecclesia in America (The Church In America), in which he entrusts America to Our Lady of Guadalupe, whose image bears the symbolism of her pregnancy.

“Through her powerful intercession,” he writes (No. 70), “the Gospel will penetrate the hearts of the men and women of America and permeate their cultures, transforming them from within.”

If we truly join Mary in her Yes, what vast changes will the years ahead bring?