Catechism of the Catholic Church §491 — excerpt
Through the centuries the Church has become ever more aware that Mary, "full of grace" through God, was redeemed from the moment of her conception.
This translation is under copyright, so only the cited words are quoted here. Follow the link for the full text. Translation: English translation of the Catechism of the Catholic Church, 2nd ed. (Libreria Editrice Vaticana), as posted at vatican.va.
Also cites: Pius IX, Ineffabilis Deus (1854): DS 2803