Avira DeArah,
You are looking at this debate as a halachik issue and there should be no exceptions to murder. – except where halacha allows.
However , in America, this is not a halachik debate.
Even the Mississipi law allows abortions before 15 weeks. Why? Can you commit murder on a human being before 15 weeks?
It allows an exception after 15 weeks for severely deformed babies . Can you commit murder on deformed babies after they are born ?
Most states have a rape exception. Can you commit murder on a baby born from rape?
The Mississippi law and all other laws on abortion in America, still allow Halachik murder on its own terms.
American law will never codify the halachik definition of abortion. It will always be inconsistent with it.