To me, the issue reduces to this: When does human life begin?
One of the most interesting questions I heard during my years in school was: How do we define life? It’s not as easy to answer as one might assume. Is digestion or respiration life's defining component? If so, some chemical processes mimic the functions and would demand inclusion. Is sentience the requirement? That would exclude a whole host of what we consider life, including the beautiful oak tree I’m looking at beyond my back deck. Is the ability to propagate the standard by which we measure life? Here again, some inorganic processes involving protein strings might classify by such a definition. Life, therefore, is a lot like pornography: You might know it by looking at it, but defining it is a different matter.
But that’s exactly what we must do if we’re going to get anywhere in our often rancorous discussion about abortion. Between conception and birth, if there is a point beyond which life can be reasoned to begin, a woman should have a choice about her body prior to reaching it. On the other hand, once that point has been crossed, it becomes our Rubicon.
If we focus on the issue, rather than call each other names, we might find our way out of what seems an inextricable impasse. For a nice treatment of the subject, take a look at the following: