The parallel does hold. The women are not prisoners of any moral viewpoint. They are "prisoners" of nature. If they participate in the volitional act of sexual intercourse, it is nature, not some moral or religious point of view that "imprisons" them.   They cannot then decide to kill the product of their volitional activity.

They have the absolute right to decide not to participate in reproductive activity. Once they have decided to participate in the activity though, it is an act of nature, not religion, that makes them pregnant. And it isn't religion that makes a society that does not allow one person to kill another for inconveniencing them. The non-religious believe in the rights of life too.

If a woman volunteerly picks up a hitchhiker, she cannot decide to kill that hitchiker (unless, of course he threatens her life) just because she suddenly wishes that she hadn't picked him/her up in the first place. The time for her to have decided not to have a hitchhiker in her car was before she picked one up. The hitchhiker is no less a person just because it's riding in her car.