Of course life starts at conception, because the original cells have to be living in order to grow in the first place. Literally no one is debating the fact that the cells are alive, because they would have to be alive for it to even be a living fetus (even though you and science are likely talking about a different meaning of "life" here). The entire abortion argument is about bodily autonomy and consent...the "life" of the fetus is completely irrelevant. YOU have sole and total say over who can or cannot use your body, at any time, for any or no reason. So to answer your question: yes, it is absolutely justifiable to abort an unborn baby if the mother does not consent to it using her body, even if her reasoning is purely because she doesn't want to be pregnant anymore...