Yup, pretty clear this is a way to oppose all abortions by de-legitimizing the idea that yes, a woman can be impregnated during rape; ever heard of the Moors? If you can create doubt about the victims, it's easier to justify ethical and political stances against abortion. Notice, Romney/Ryan put out a statement saying abortion in the case of rape should be legal; being opposed to it remains a controversial, losing argument. But this whole thing has exposed a long standing far right battle on this issue.
Akin's sin isn't that he believes this nonsense, at least in the eyes of many on the right - it's that he said it out loud.