I disagree with the "except in the case of rape or incest" illogic.
I have heard most of the political and emotional rationale for that position and though they are seductive, they are not convincing. From the political perspective, one might suggest that there is a better chance of getting anti-abortion legislation passed when exceptions are allowed and I have no reason to doubt that assertion. From the emotional angle, we all have heart-felt sympathy for the victimized mother.
There is a powerful reluctance to force a woman to continue her physically demanding and emotionally draining role in the most divine function of God's nature when the initiation of that process was without the mother's normally assumed consent. We would be assigning to her the responsibility to carry into this world a new soul who will be a seemingly unholy combination of her own self and of a man who is either freightenly unknown or sinfully familiar.
There is, of course, the almost inescapable temptation to assume this new person will somehow not be good because the genetic code of a rapist was used in his/her construction. Or that the new person will somehow not be complete because of the potential for physiological problems to arise when daddy is grandpa.
Adoption is always an option when the post-birth burdens outweigh the natural desire of the mother to nuture a child which is, after all, still half her.
On any scientific or logical rationale, assuming human life has value, I would ask two questions:
1) Does it continue to grow and change via natural biologic process?
If the answer is 'yes', then it is alive.
2) What will it be if the process is allowed to complete?
If the answer is 'human', then it has rights.
Pregnancy brought on by rape is a sticky subject for many pro-life advocates. Whether the victim is an adult or a minor, they will suffer psychological damage from the rape itself. Add to that their requirement to carry the results of that awful experience for nine months, and then go through the birth process.
I confess that if this happened to my young daughter, I might lose my soul, because I cannot imagine allowing, or forcing, her to go through this. If it happened to an adult, I really could understand if she chose abortion.
Are all moral decisions black and white? Or do circumstances factor into every particular situation?