When the Archangel Gabriel announced to the Blessed Virgin Mary that she would bear the Son of God, he also told her of her cousin’s miraculous pregnancy. We read in Luke 1:39-40 “…And Mary rising up in those days, went into the hill country with haste into a city of Juda. And she entered into the house of Zachary, and saluted Elizabeth.”
At Mary's greeting, Elizabeth felt her six-month baby leap in her womb and exclaimed filled with the Holy Ghost: “Blessed art thou among women, and blessed is the fruit of thy womb. And whence is this to me that the mother of my Lord should come to me? For behold as soon as the voice of thy salutation sounded in my ears, the infant in my womb leaped for joy.” Luke 1:42-44
The first part of Elizabeth’s salutation forms the second sentence of the Hail Mary. Mary, in turn, overflowing with joy and gratitude for her election, responds with the prayer of the Magnificat.
Elizabeth’s salutation to Mary as “Blessed…among women” and “mother of my Lord” can be viewed as the first expression of the Church’s devotion to Mary as the exalted handmaid of the Lord, and true mother of God made man.