I think rape is a obvious exception. I think there can be a suspension of whatever personal morals usually apply in cases of rape, regardless of what the Church says.
In situations where the pregnancy has occured because of failed birth control methods, it should not be considered in the dry way it often is, as simply the next preventative method. The impression I get from you is that it's exactly the same as a condom, the pill, the coil and other assorted means for avoiding pregnancy, and that's not how I could ever consider it. It's something entirely different as far as I'm concerned, something I'm not necessarily against, as I said, but that I believe warrants more thought.