I discussed the "exceptions" in this post
http://www.freerepublic.com/focus/f-news/1320881/posts?page=48#48
The baby is her baby. He or she is just as much a possessor of the inalienable right not to be killed as she is. If the infant does not have the right not to be killed - an inalienable right not dependent on any circumstances - then how to justify the right not to be killed of any unborn child???
[The next bit sounds very unemotional and clinical, but that's the only way I can contemplate this question, by attempting to be "clinical." I base my discussion on comments by Gilbert Meilander in his book "Christian Bioethics, a Primer." I'm still opposed to the finality, the irreversibility of death and am convinced that we humans are more adaptable and able to survive horrible circumstances as long as there is life.]
The only exception would be is when a woman considers the pregnancy a continuation of the assault. This might happen in cases where the woman perceived that her life was actually at risk during the rape. Consider a woman beaten or injured, or one who is held at gunpoint, or one who is believes that she has been exposed to HIV. There are also the women who are truly endangered by pregnancy. And the ones whose husbands can't bear the fact that she has been raped, much less that she is carrying the rapist's child.
Back to what *I* believe: I'm afraid that the reason for the exception for rape is actually a response to those who want to forget that she was raped, possibly, especially, her husband and father. In the days where women belonged to their husbands or fathers (and in the parts of the world where this is true), the male reaction is to kill the child of the rapist who stole "their" property - the woman's sex, fertility, and offspring.