I’ve always gone with 12 weeks - there’s some vids around showing response to stimuli.
Pain or not, the question is distress.
I’m pro-choice, irreligious. Can’t stand the thought of a live being in distress at the hands of another.
For me, a zygote is a human life. Not a fan of abortion, but wouldn’t argue against it so long as there’s no suffering.
I’m familiar with the A-Z.