Obviously that would be concluded in the trial. All women would be tried for third-degree murder to see if it was indeed their own bodies that killed the child, hence themselves unintentionally murdering a human being by your stance.
I used the word "some" because I would think there are instances where it was not the mother's body that denied the child, so she would be seen not guilty. I could be wrong though.
It would be hypocritical for Pro-life individuals to call "murder" under the specific situation of first degree but not under second and third degree. You don't get to pick and choose murder just to meet your political position.