The bible does say that God knew us before we were in our mothers womb, or something to that effect. I have no idea what that means, but i assume that would be where that concept came from.
That's Psalm 139... everything in the psalm speaks about what God knew AFTER sperm had joined with egg, not prior to it. As I mentioned before, using that argument to argue the legitimacy of abortion is indefensible.
In Jeremiah 1:5 KJV, God says, "Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee, and I ordained thee a prophet unto the nations." This highlights that God has an intimate, pre-existing knowledge and purpose for individuals before conception or birth.
I think this is the one i was talking about. Like i said, i dont know exactly what it means and i try to avoid building a biblical theory off one verse