what it all comes down to is the belief that pregnancy is god's will, that babies are gods creations, and women's bodies are just the vessels he uses to make life. it's the belief that pregnancy is passive. anything the woman does to actively interfere with god's plan is her playing god and acting above her station.
but we know this is bullshit, that women's bodies make unconscious decisions regarding pregnancy, from conception to miscarriage, prioritizing her welfare above all else. if binge drinking during pregnancy is an active choice that creates a disabled child, materially so is continuing a pregnancy that you know will create a disabled child. there is no difference in outcome for the child who has to deal with the lifelong disability. and there's no material difference between miscarriage and abortion, either, except that one is a conscious choice. fundamentally, what people are uncomfortable with is women defying what they see as divine authority by exerting her own will over creation. but she's the only god in this scenario, because nobody's getting created without her.