Why should I? Wasn't the claim ALL of the prayer to Mary is from the Bible? "Mother of my Lord" was obviously not the same thing as Elisabeth saying, "Mother of God". Try not to hurt your brain digging too deep, it's really as simple as disputing the claim one person made - though there are probably others who think it's the same thing.
BTW...while on the same subject...nowhere in the Bible is "pray for us sinners now and at the hour of our death", found either. "Amen" is a given.
How so? What did Elizabeth mean by calling an unborn child, "My Lord"? Do you know how many times God is referred to as Lord in your precious bible?