Let me ask you this -
In nature, some creatures kill their newly born cubs. Are they murderers in your eyes?
Please don't tell me it's a different thing because these are animals and we are talking about human beings.
My point to make is that there are unseen, unconscious elements, instincts if you will, that drive behavior, and women who feel the urge to do an abortion follow their inner voice, just as the animal chooses to kill her cub out of mercy and empathy.
And no one but the mother can feel and know that instinct.