As others have pointed out, this analogy only has
prima facie relevance when the pregnancy is the result of rape.
Additionally:
- there is no blood (familial) relationship between the men in the analogy
- expectant mothers are not kept chained to gurneys in abandoned basements
- life expectancy is significantly shortened by kidney transplants; not the case with pregnancy
- the operation as depicted would carry a significant risk of death; not the case with pregnancy
- expectant mothers aren't brutally attacked by the state; the state is not a single unhinged man operating independently and without oversight
- the chained man isn't the only man who can assist the dying man; this circumstance doesn't apply to pregnancy
- a kidney transplant isn't the only treatment option for the dying man; this circumstance doesn't apply to pregnancy
A fairer analogy for pregnancy via rape would be if the state mandated that everyone with extremely rare Z-type blood must regularly donate blood for sake of other persons with Z-type blood who couldn't receive it from anyone else. The law would except only Z-type blood holders with a significant risk of dying as a result of the donations.
Get that into a vignette and we'll discuss it.
I'm not getting into a vignette, but you are missing the point on this one.
When a woman consents to any kind of sexual contact, even a kiss, she gives a particular person or persons consent to touch a particular part of her body with particular parts of the body of that person or those persons or even with an object. However, she does not consent to other persons, body parts, objects. If you get to have sex with a woman, that does not mean your adult son gets to have sex with her on the basis of her consenting just to you.
Why would you imagine that her consent to have a man's penis in her vagina is consent to have an embryo implant part of itself into the flesh of her endometrial wall, stay implanted for nine months, and take oxygen and nutrition from her blood and put excrement there, and tear her flesh on coming out of her at the end? Especially if the people having sex used contraception, thus expressing their intentions?
Even if an embryo were a person, then, it could not be treated as having received consent to implantation. But the real issue is not that the embryo that is de facto raping the woman, since it is legally incompetent.
Rather, by making and enforcing an anti-abortion law that forces pregnancy to continue, the law fails to recognize the woman's rights to privacy and liberty which are otherwise recognized. That law makes all citizens guilty of that failure, which is why pro-choice people do not want to make such a law. It is also as if the law were using the embryo as a rape tool, and a case could in fact be made for that view.
Our constitution does not recognize an embryo's right to life, but even if it did, neither you nor the law would have a right to rape the woman with the embryo.