It's not only the pregnant women who would be criminalised, is it? It's the doctors treating them. Would a doctor in this scenario be put on trial and forced to prove that what he did was medically necessary and that the foetus wasn't viable?
Because if the woman was on trial for murder, then the doctor is equally culpable. Possibly more so, since the doctor is the one actually carrying out the procedure.
A doctor carrying out an illegal abortion in Texas can be sentenced to life in prison. I believe that's the harshest punishment but other states have imprisonment, fines, and suspension of medical licences.