Normal case scenario: (fetus will live, mother will live, etc) Whether the Fetus is living/human or not should be irrelevant. It will, no matter what we want, be a live human when born, so killing (or removing if you prefer) the fetus earlier in the womb, you are in fact directly preventing it from living.
Now if you're going to argue that in this case, in the fetus is born, the mother will most likely die, (Putin likes to bring this up) and saying it is basically a life or a life, then I will ask you: If you saw a man, obviously drunk, getting into a car near an extremely crowed street, at night, etc, and the odds of him crashing and killing someone are just as high as the mother dying, (and you are the only one who saw him getting in his car) are you going to shoot him to prevent other innocent(s) from dying? It is basically the same thing, yes?
In other words, we should take every chance, no matter how small, to try to have both of them live. If only one makes it, so be it. But by killing the fetus earlier, you are ensuring that a human person does not get to experience the world at all.