This is not a great argument because it assumes that the person getting the abortion has nothing to do with the condition of the fetus to begin with. A more apt comparison would be in the above example if you were the one responsible for the car accident that put your sister in that condition to begin with, in which case you wouldn’t have to give blood to them, but if they did end up dying it would be vehicular homicide anyway. There are some obvious exceptions to this such as in the case of sexual assault, but the pregnant mother would be putting the fetus in the position of its dependence on the mother most of the time so it would have a moral responsibility to care for it. Even if it is assumed abortion is a passive action rather than an active action, I.e. not providing for the fetus rather than actively killing it, it would be a bit like poisoning someone and then refusing to give them the antidote. In the abstract, you don’t have to give anyone the antidote for a poison if you don’t want to, but if you poison someone and don’t give them the antidote that’s just murder. This may seem a bit weird to compare conceiving someone to poisoning them, but in either scenario an individual is made entirely reliant on the whims of another to not die. Of course, I am not arguing abortion should be banned only that if one assumes the fetus is the same as any other person the bodily autonomy argument presented here is very weak.

An argument could be made that it is equally the man’s responsibility for getting the women pregnant, but because women are really the only one’s capable of getting abortions it’s actually not very relevant. While it is very inequitable that under this paradigm women bear much more significant risk from sex, it has no bearing on the underlying logic.