Somehow, the false idea that the life of the baby should be saved at all costs (even if it means the death of the mother) has been perpetuated.
Not the idea that the baby should be saved at all costs; the idea that intentionally shortening the life of a person - which has been deemed to include a fetus - is murder except in certain extenuating circumstances, none of which apply in this case (e.g. killing in a just war).
It doesn't matter that an abortion in this case would only shorten the fetus' life by only a few hours or days; by Catholic doctrine, an abortion to save the life of the mother would have been the moral equivalent of killing an adult with a terminal illness to harvest his organs, and is unacceptable.