The feast was celebrated in the east before the west, but by the 5th century it was celebrated in France and Spain on the Sunday before Christmas. In Rome, even before the 7th century, January 1 was used as a celebration of the Maternity of the Blessed Virgin Mary. In the 13th century and 14th century, the Feast of the Circumcision of Christ had come to replace the Marian feast on January 1. The celebration of the Feast of the Circumcision on January 1 was expanded to the entire Roman Catholic Church in 1570 when Pope Pius V promulgated the Roman Missal for the entire church. In 1914, the feast of the "Maternity of the Blessed Virgin Mary" was established in Portugal, occurring on October 11. In 1931, this feast was extended to the entire Roman Catholic Church by Pope Pius XI and maintained on October 11. Following the Second Vatican Council in 1974, Pope Paul VI removed the Feast of the Circumcision of Christ from the liturgical calendar, and replaced it with the feast of the "Solemnity of Mary, Mother of God. Traditional Roman Catholics continue to celebrate this feast day with the old name "The Maternity of the Blessed Virgin Mary" on October 11.
The feast is a celebration of Mary's motherhood of Jesus. The title “Mother of God” is a western derivation from the Greek, “theotokos,” literally translated God-bearer. The term “theotokos” was adopted at the ecumenical council at Ephesus as a way to assert the divinity of Christ, from which it follows that what is predicated of Christ is predicated of God. So, if Mary is the mother of Jesus, she is the mother of God. Therefore, the title “Mother of God” and the “Solemnity of Mary, Mother of God”, which celebrates her under this title, are at once Mariological and Christological.