Just adding my thoughts to this one since it came up among some friends of mine the other day. Now I should preface that none of them is anti-choice in the sense that they would see the right to abortion taken away entirely *and* that the majority of them are well-versed in fetal development (med school), but some of them haven't truly examined the social/political angle of the issue and still feel somewhat attracted to the more emotionally charged lifer arguments and favour "restriction", whatever that means.
What I did -and what I think works for moderate people whom you don't wish to alienate- is to keep reminding them that all those arguments are fine & dandy when applied to themselves only. That way you get to acknowledge their squicked-out-ness, you don't need to invalidate their heartfelt doubts (and possible belief that fetii are "babies"), but you steer the debate away from political waters. It becomes more about the personal and less about the political. In this particular case, it worked.
'Course I will be making a point of subtly introducing fascinating topics like bodily autonomy, access to adequate medical care vs. education and affluence, religious spins & rhetoric and the social burden of pregnancy in the future.