> I don’t understand how you can say something like that with a clear conscience

Not the gp, but my position is that equating a fetus to a person is a fallacy based in the idea that it's a potential person. Which however means it's actually not one. Human beings have language, thought, self-awareness, memories, knowledge, experience, friends, family, hopes and fears. A fetus, wild speculations aside, has none of these. A dna is just a long molecule, not necessary and not enough to attribute humanity. A developed brain and a sense of self instead are both necessary and sufficient. A fetus has neither.