ISB ~ Luke 1 v43

mother of my Lord:This title reveals the twin mysteries of Jesus’ divinity and Mary’s divine maternity (CCC 449, 495). Note that every occurrence of the word Lord in the immediate (1:45) and surrounding context refers to God (1:28, 32, 38, 46, 58, 68).

• Mary’s divine motherhood was the first Marian dogma expounded by the Church. The Ecumenical Council of Ephesus (A.D. 431) defined her unique relationship to Christ and honored her with the title “Mother of God” (Gk. Theotokos). This was reaffirmed in 1964 at Vatican II (Lumen Gentium, 53).