well the possiblity is there that it could become a human...The taxonomical classification of the human being which is in the womb is based on its DNA, which remains the same from conception till death, and its vitality is based on the process of cell division. Thus, it is not merely possibly human or alive but truly so, and that which is being gestated is a living human being.
An unborn child is a human life that possesses the potential of becoming a thinking being, which is how many define personhood. The fact that a human embryo is biologically human is an established scientific fact. For that reason, it should be protected from violence -- because, if left to it's natural course, it will develop into what even you would consider a human person. There is the certainty, not the possibility, that this will happen, save accidents, miscarriages, malformations, or deliberate acts on the part of an abortionist.