I am confident that forcing a girl to go through 9 months of pregnancy and labor - with all the physical dangers, lose of freedom, and physical pain involved - would be determined to be cruel and unusual punishment for the offense of being raped.
Given that only poor women couldn't get an abortion by going to another state or country, it also would be unconstitutional under equal rights provisions and equal due process provisions. Being anything but poor and in real terms abortion is legal. Have an abortion but be poor and you are a 1st degree murderer. That doesn't fly.
Cheap, fast and dirty abortion clinics would spring up on all borders and the Islands. Poor women would have to find some butcher in the slums and then also risking criminal prosecution.