Catechism of the Catholic Church §2674 — excerpt
Mary gave her consent in faith at the Annunciation and maintained it without hesitation at the foot of the Cross. Ever since, her motherhood has extended to the brothers and sisters of her Son "who still journey on earth surrounded by dangers and difficulties."
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: LG 62