The libertarian worldview is quite clear: you have a right to do anything you want so long as you do not harm, defraud, coerce, or otherwise violate the rights of others. Such a simplistic political philosophy fails to address the most difficult and important questions facing man and society. In the case of abortion, libertarian philosophy is at an utter loss in being able to provide answers to the question of when life begins or at what point does an individual have rights. Libertarianism takes from granted that these questions have answers, and hence cannot itself answer them.
To answer these questions you have to draw upon some philosiphical or religous system to which libertarianism is extraneous. That's why libertarians cannot and will never come to a consensus on the matter.
The abortion debate was one of many things that made me realize how bankrupt a philosophy libertarianism is.