Looking at the "Acquisition of U.S. Citizenship by a Child Born Abroad" page, it seems that there are some combinations where the targeted baby may not be an American citizen by default. So, what happens when the American parent tries taking the baby with them to the U.S.? Does the baby get deported as an illegal immigrant? Possibly to an orphanage/foster-care if the other parent isn't there and/or the U.S. parent doesn't want to travel? Is there a way for the American parent have the baby converted to a (naturalized) citizen?
Oh, and that page doesn't seem to cover what happens if both parents are U.S. citizens, but not in wedlock. Does anyone know the policy in that case?