There's another thing going on here with this kind of rhetoric, one which wasn't as immediately apparent to me.
Akin went on Mike Huckabee's show today, semi-sorta-apologized, and then "clarified" by saying he was only referring to "forcible rape" (as opposed to casual, "oops I just slipped and my penis fell in you" rape??)
Sound a little weird? There's a method to the derpness. See, the rape exemption/"loophole" (from their POV) creates problems. If you allow it for forcible rape (or what they sometimes refer to as "legitimate rape", a neologism that is just wrong on so many levels), then what about statutory rape? Which is, of course, defined as any sex (even consensual) with a person not of age of consent, as defined by their home state.
OMG 15-year old girls would get a free pass for abortions!!
Basically, they see it as a slippery slope problem -- make an exception for rape, you have to start considering exemptions for other valid reasons. BUT...if you can make some kind of case that "real rape" can't produce a child, then you don't need to bother with exemptions for it. Problem solved. Except for that "incest and/or life of the mother at risk" exemptions.
I can't WAIT to hear the talking points on those.
"Incest isn't a terrible thing! Why, it was a practice of royalty for centuries! It strengthens the gene pool! It prevents miscegenation!"