Suppose we have Star Trek technology. A pregnant woman can go in for an abortion, to have the embryo or fetus immediately teleported out of the woman into a large fluid filled incubator designed to sustain human life.
There is now, no pro-life issue cause the life that was inside the woman is now sustained.
There is no pro-choice issue cause the life exists externally and no one can mention a woman's body being her choice.
At what stage of development can that human life be terminated?
What's missing, I think, is how society would change if such a thing were possible. It means that people could create children with apparently no responsibility for raising them. There would be no need for birth control at all. If a baby happens, just teleport it.
So then, how do all these unwanted teleported babies get raised? Who nurtures them? Who pays for their support?
While as many as possible might be adopted out, I suspect that society would soon begin to feel that they were a drain on resources, and would either heartlessly try to minimize their care (futuristic orphanages run by robots?), or compassionately start putting pressure on parents not to teletransport and instead to take responsibility for the children they produced.
Once you start heading down the first path, seeing the vat babies as a drain on resources, you have two tiers of children, one kind more loved than the other, and I suspect that triage would start to be applied... "Maybe we won't keep this one in the vat, because it'll only live a few months with that birth defect anyway, and will cost a lot of money. And maybe not that one, because it'll only live a few years. And maybe not that one because it'll live to old age but won't contribute enough to the workforce to pay its raising..." So the pressure to abort the vat babies would grow.
If you head down the other path, and try to discourage parents from teleporting, then the vat technology will begin to wither, because even though it's an option, it'll be one that's used less and less. Rather than face the stigma of being a (*sneer*)
teleporter, people will use birth control or other methods, depending on how bad the stigma is. But the existence of birth control doesn't prevent the existence of abortion today. It would depend on whether the guilt of knowing your teleported child would be spending its life working underground in the salt mines on Mars, was worse than the guilt of aborting it, as to where abortion fell among the options.
And either way, we'd be right back where we started.