How is this ethically different from having an abortion?

Most people do not consider a tiny fetus in its first few weeks to be the same thing as a human - rather, it has the potential to be a human life. so if a person believes that, it is not murder. If a person believes that life begins at conception, then abortion is murder. In the middle ages, my understanding is that a fetus was not considered "alive" until quickening. now, many churches say life begins at conception, now that pregnancy is better understood. It all depends on what your belief is about when is the beginning of human life.