Sometimes the circumstance that makes continuing a pregnancy a threat to the life of the mother arises during the pregnancy.
I know of no one - No matter how far to the right you go - No one objects to abortion in the face of a true risk to the life of the mother, especially if the life of the child will be lost anyway. No one. That is not the argument.
The argument comes when the 'life of the mother' exception is abused - And it has been abused extensively - to where 'welfare of the mother 'comes to include hardship, or psychological well being... And next thing you know, it means anything at all, and nothing at all... and the exception becomes a rubber stamp.
Likewise the incest and rape clause. While I am generally against this exception, as enumerated elsewhere on this thread, I would be willing to entertain the idea in the case of true rape and incest. But again, that is not where it goes. If all a woman has to do is declare rape, with no criminal investigation, nothing but her word on the matter, then again the exception becomes a rubber stamp.
Despite the whining and crying and throwing dirt in the air, it is not a matter of compassion, but rather a matter of abuse of law... and the two exceptions becoming the very means of allowance. And we are right back to abortion as birth control.