Here is a good essay (The Right to Life and the Irrelevance of Rape) by Michael Paulsen. http://www.thepublicdiscourse.com/2012/09/6229
Here is key portion of his argument: “The fact of rape is irrelevant. Rape is tragic, awful, horrible, gut-wrenching—an unspeakable crime of great emotional harm—but rape is essentially irrelevant to the morality of abortion. The issue is the human status, or lack thereof, of the unborn child—whether he or she has a right to live, or may instead be killed for reasons society deems sufficient good cause or simply leaves to the mother’s unrestricted choice. ”
Richard M.