If it is a negative right when rape, it is still a negative right when the sex was consensual. "not to gestate a child when you don't want to". Both are negatives. But people perceive the rape exception as "more valid" because they claim that a woman who have sex no longer should be allowed to decide to not gestate. And there is religious rooths on this belief.

Also, in practice, this exception doesn't work most of the time, since it requires a rape accusation and when a woman accuses a men of rape, she is the one on trial. So you might be very well find that a woman is raped by someone know to her (and posibly respected in her community). After the trauma she found out she is pregnant at 8 weeks. Here, if there is no-fault abortion, she can just go an abort. If only rape exception is made, she needs to put the denounce, prove it and by the time that happens (assuming she can prove it), it might be too late for that and be in the late term that you wanted to avoid. Or she might have been raped but not prove enough to prove at a trial and be forced to gestate her rapist child. At this point, the rapist might decide that he wants parental rights and if she doesn't want to raise the rapist child, she would be the one paying child support to her rapist.

Abortion is a negative right always: "I don't want to gestate this embrio/phoetus" (depends on how far of the pregnancy you are). You don't want to gestate, yet, if abortion is denied, you are forced to gestate and give birth. Remember, abortion when raped also needs medical asistance.

For example: A woman has sex with her husband that she loves, she becomes pregnant but in her case, the pregnancy would put her health at risk. She doesn't want to gestate. You deny her medical assistance for an abortion. Here she can try to self induce abortion. Would you make this legal or would be banned? Self induced doesn't require assistance nut as we know, she might hurt herself and end needing medical assistance anyway. On the other hand, if you completely ban abortion, you are forcing her to continue a gestation against her will. Denying her a negative right to not continue an unwanted pregnancy/gestate an unwanted child.

And lets consider other situation: a man who tampers with the woman's contraception. He wants to have children with that woman. She doesn't want to get pregnant. He trick her to have sex with a condom that he has brought and has a hole, she gets pregnant. Now proving that might be a nightmare. Would you force that woman to continue the pregnancy if she doesn't want to? And after that, if she doesn't want the child but the men does and refuses to give it for adoption, she would be the one paying child support.

Implicitly in the rape exception is the part about thinking that it is OK to force a woman who had sex to gestate an unwanted pregnancy and to give birth and rape doesn't count, because it was forced sex. But no, having sex and gestating are two different things.

And once you start forcing women to gestate, you might as well start considering that their bodies fulfill a "public service" and if birth rates are too low, then they should be forced to go through a pregnancy, so why not force them to have artificial insemination and give birth for the good of the country? So I stand by what I said: all pregnancies should be voluntary and willing.