Its simple really . . .
Consider the following premises:
- Women are moral agents.
- Abortion is a kind of murder.
- Murder either committed or procured by a moral agent should be subject to some kind of punishment.
Pro-lifers profess to believe (2).
(3) is self-evident.
The recent Donald Trump abortion kerfuffle clearly showed that the pro-life movement does not believe that women should be subject to any kind of punishment for procuring an abortion.
Therefore, the pro-life movement rejects (1).