The idea of Abba up is a play on Romans 8:15 "For you did not receive the spirit of bondage again to fear, but you received the Spirit of adoption by whom we cry out, “Abba, Father.”
They are saying the baby is saying the Father is up, I do not see it as a prophesy. It is a baby repeating what they have heard, my grandson has repeated Greek word when I was studying, it is not uncommon.