Abortion doesn't negate a childs right to live. It negates a phoetus right to use the body of a women to develop into a baby. It affects body autonomy because it affects the body of a woman. Organs atrophiate to make space for the phoetus, it feeds directly from the woman's body and can cause lasting physical consequences like losing teeths, developing lasting illness like diabetes or even death of the woman.
In any other situation where the body integrity of one person is considered against other person's life, body integrity triumps. I gave you examples with blood, marrow and organs donation. Yet, in this situation for your argument to work you have to:
1. Ignore how pregnancy affects directly a woman's body.
2. Ignore all the other situations where a children's life requires that other people is denied their body integrity, the law says that the child dies. The children needs marrow donation by a father? It dies. The children needs an organ donation by a death relative but the relative is religious? The children dies.
3. Adoption won't magically erase the 9 months of pregnancy and lasting physicall consequences. If a woman becomes blind because diabetes, then adoption won't make her see. If she dies in childbirth or because the pregnacy is not viable, then adoption won't resurrect her.
4. The phoetus is not independent. If you remove it at four months from the womb and give it up for adoption, it won't develop. It needs the woman's body to develop.
The definition of voluntary and involuntary applies to pregnancy too. But conveniently, you need to forget that it affects a woman's body and that if you deny abortion, is that pregnancy stops being voluntary and becomes forced. Thus becomes a violation of body autonomy.
As for the "voluntary action of having sex", I remind you that not only rape exist, but that by using contraception, they are saying that they don't want to become pregnant. Agree to sex doesn't mean agree to pregnancy. That is a huge fallacy.
The idea of "tacitly accepting" that you want to apply, is only applied to force a pregnacy and deny body integrity, because you won't apply the same absurdity to anything else. Not to donation (yuo can decide that by diying you "tacitly" agree to donate your organs, for example). Or that by leaving your keys in the car you "tacitly" agree for others to take it. Or that by being a compatible marrow donnor you "tacitly" agree to donate. I could go on, but the very idea is absurd because people use contraception to expresely say "I don't want to get pregnant" yet contraception fails (and sometimes it is tampered with). So no voluntary at all. Why do you lie to yourself on this?
Your point could be resumed in "I don't consider a woman has a right over her own body if she gets pregnant because I think someone different that the woman should be able to use her body to develop".
Besides, if the phoetus is "independent", taking it outside the womb won't kill it. It is independent, it would survive. By claiming it would be "murdered" you are showing that you do know it is not independent. Think of abortion as a woman saying "I don't want this in my body". If once outside the body can't survive, it is no different than someone who needs marrow or organ donation and doesn't get it. This time the phoetus doesn't get a womb and blood donation plus space inside a woman's body to develop for nine months. If it is independant, then you can put it into an incubator.
Besides, considering that USA doesn't even provide free healthcare to pregnant people and that some of those phoetuses would die because lack of healthcare, I don't believe that you care about "murder" or phoetuses.
If you need to lie about phoetuses being independent (if they were, it won't matter if you extract them from the womb), the "give it for adoption" as if that erase the nine pregnancy months plus giving birth which is painful and has a difficult recovery. And the fact that having sex doesn't mean voluntary agree to pregnancy because using contraception means just the opposite.
And then the exception you made with rape. Supposedly there is a life there too. But you make an exception because you do know that the pregnancy is unwanted and you only want to punish women who have sex for pleasure and fun.
Your problem is not about murder, is about your idea that women't should have a right to use their body autonomy to have sex for pleasure and fun without being punished with an unwanted pregnancy. So yes, this is about body autonomy all the way.
I say it respectfully, many of your premises are false. It is obvious that it is about body autonomy. Think why you really want to make exceptions. Then turn it around and ask yourself "if someone were to take away your body autonomy to save a children's life", how would you feel? For example: by making blood and marrow donation mandatory. It won't kill you, it would save lives, some of them children. Sure, it could be a little painful, but then again, giving birth is even more painful and you are OK with this. Are you a murderer for not donanting your marrow? It won't kill you, so why not making it forced? This what you are telling women, that they can't decide over their bodies and lives.
