The child has a right to life just as much as that woman had the right to not be raped. Her rights were violated by the rapist. Aborting the child would be violating the child's right to life. I certainly feel deeply for anyone in such a position, but that doesn't mean I would sympathize with them enough to believe they have the right to then cause harm to another. A woman's body is required to produce life, therefore an unborn child has no other option then to rely on her, no matter the reason for conception. The rapist made a choice based on his own selfish feelings and beliefs in what he was entitled to, isn't that exactly what happens when we allow abortion as a "choice?"
Having an abortion is just as wrong as the rape itself.