Multiple VISIBLE pregnancy stages more "wish" than "required". But at least should have multiple "logical" stages like "fertilized" (not visible yet, maybe can somehow prevent becoming pregnant), "pregnant" (not visible yet), "pregnant" (visible), "late pregnant" (visible, slower movements), "birth". This gives sense of progression instead of being binary toggle which is boring.
That way you have many stages of pregnancy without needing lots of art work which is very hard, I understand.
Also XXX animations should be better, multiple stages. Right now is just "BAM" instant fucking. That's not good immersion. Should start out with "struggling" (not sex, enemy trying to subdue PC), "undressing/foreplay" (enemy has subdued PC, now is trying to engage sexually), plus "sex" stages, "finish" stage, and "recovery/after" stage. If you want good example of how to do it right, look at Anthophobia or Parasite in City. Parasite in City also does pregnancy very well without needing tons of visible animated stages.