The purpose is to prevent murder of unborn children. Don't over-intellectualize things until you can't see the fundamental issues.
These factors make it quite impossible to protect a baby unless his mother has both the power and the sill to save him. His insecurity is absolute when his mother can make an end of him with a handful of birth control pills and the flush of a toilet.
The results of an early self-abortion such as this cannot be distinguished from a natural miscarriage. There's no way to prove it was an abortion unless you want to do a forensic autopsy of all baby parts found in vaginally bleeding women in the ER. And even then, the proof would be iffy.
Therefore (ahem: dealing with concrete details, not over-intellectualizing here) it is futile to try to stop abortion by focusing punitive measures on the mother.
Most women do not abort by self-administering OC's or prostaglandin suppositories or pennyroyal and blue cohosh tea, or anything of the sort. Most women go to abortionists. The only practical way to stop (most) abortions is to shut down he abortion industry, which requires successfully eliciting the cooperation of women who HAD abortions, who can testify against the abortionist. They will not do so if they think they can be prosecuted.
That is why starting in the mid-19th century, all 50 states eventually made the decision to fashion their laws against the laws against the professional criminal abortionist, the doctor, and did not prosecute the women. How many states again? Fifty out of fifty.
There's a reason for that. Think about it.