What happens with cancers, necrotic tissues, pulled teeth? If it has value, it's studied, if it's worthless it is discarded. Just because a melon seed begins to sprout from my compost heap means I'm obligated to transplant and grow it. It has no objective value to me and I'd do what I want with my perceived garbage. Because you ascribe a moral value to a non-viable fetus or embryo doesn give you or your conservative friends the right to force it to term.