OK SC.
Of course, again, I think that just because the interpretation is hard does not mean one cannot come to a decided opinion on how to interpret it (though there will be disagreement); in particular I think you're reading in when you ascribe a "Jesus changed everything" source to the personhood of infants. As elaborated earlier in this thread, much of the case for that is based on the OT. Naturally, this entails a reading of Exodus 21 different from that which you espouse, but there are ample such to be found.
(This is NOT an argument that Exodus 21 should not be discussed, or that your position is prima facie absurd, but that one can decide that it is wrong and still have a firm opinion on such; and, that one is not completely flouting ancient interpretation in so doing).
@Marti: Nothing new in pointing this out, but this all turns on whether one considers a foetus to be a human or not. If one does, for whatever reason, then the logic is NOT that it is a personal choice respecting the woman's own organs.
Let's take an analogous case. A hundred and fifty years ago there were (I presume / vaguely remember, I don't claim to be a scholar, but it doesn't matter anyway for present purposes if this is historical or just illustrative) people who believed it was fine for a slave owner to beat to death his slaves, because black people were not humans, and were instead his property.
Now, the fact is, this is a perfectly rational argument, _if one accepts the heinous view that black people are not humans_. (Well, not perfectly rational, even animals can't be beaten to death, but I digress). The point is, for any right-thinking human, the argument will be irrelevant because they won't accept the horrifying premise.
Now I'm not saying the case of a foetus is as clear, but the logic is the same. The question turns on an ideological question of what is a human, not on the question of whether somebody's organs are theirs to control. Everybody agrees that a person's organs are theirs to control, in normal life.