She gave birth to Incarnate God the Word.
I think the impetus falls on whom is responsible for Jesus' Godhood.Jesus was God eternally preexistent to Mary. Mary was one of Jesus' creations. She is infinitely inferior to Jesus as are all human beings. She contributed ZERO to His deity. Did incarnate God pass through Mary's birth canal? Yes. But not because Mary gave birth to God (as in gave Him His beginning). Mary gave birth to the incarnation of God as MAN. She contributed to His humanity, but not His divinity because had she never given birth He would have still been 100% God. After His death on the cross, He was still alive as God since He raised Himself from the Grave and a human being can not do that. (The question of who raised Jesus from the Grave is actually a great Trinity proof text since the Bible says that the Father raised Jesus, the Son raised Himself, and the Holy Spirit raised Jesus). My point is, there was never a point where Jesus as God had a beginning. He never had an ending as God. God does not have a Mother. The 2nd Person of the Trinity had a mother in his incarnation as Man - but had no mother in his personhood as God. So, as I've said elsewhere on the thread, calling Mary the "Mother of God" is unnecessarily confusing (as I know you all do not mean that she gave God his beginning as God) and everyone ought to call her what Scripture calls her and no more - Mother of Jesus and blessed.