Does it even matter if the fetus is able to feel pain though?
I mean, surely if it does and if we think it is alright to kill it we should seek the least painful way, but that doesn't address the main point: whether it is alright to kill it in the first place.
Think of it this way: Imagine I am unable to feel pain. You all certainly don't think it would be alright to kill me, right?
Perhaps the debate is about whether pain points towards consciousness? Well... Cattle feels pain and it is conscious, still...
I think the pain aspect is a red herring. The relevant aspect is the existence of higher brain functions. We should have the 'start' of life be consistent with the end of life: brain death/brain life.
And that occurs about 20-21 weeks of pregnancy.
So, at that point, care should be taken *if possible* to ensure that life is preserved.
BUT, there is still the absolute right of the woman to insist that the fetus be removed from her body, even if that results in its death.
We can attempt to ensure that death does not occur in such a case, but the woman still has the right to her own body whether or not that is possible. Otherwise, the fetus is essentially putting her into involuntary servitude.