Akin certainly has a claim, what with the "eww, lady parts, I don't even want to think about it" vagueness of his claim that women's bodies "shut that whole thing down," and he's probably the most prominent politician to make this kind of argument. But he has fierce competition from Pennsylvania state Rep. Stephen Freind, who claimed that raped women "secrete a certain secretion which has the tendency to kill sperm," as well as North Carolina state Rep. Henry Aldridge, who said that "The facts show that people who are raped – truly raped – the juices don’t flow." At this rate, I'm waiting for a Republican elected official to say pregnancy as a result of rape is impossible thanks to vagina dentata.
But the science? A study in the American Journal of Obstetrics and Gynecology estimated, from a sample of 4,008 women, that:
The national rape-related pregnancy rate is 5.0% per rape among victims of reproductive age (aged 12 to 45); among adult women an estimated 32,101 pregnancies result from rape each year.Another study, using a sample of 405 women who reported having been raped once, found a pregnancy rate of 6.4 percent. But at the lower number, the 5 percent rape pregnancy rate, that's 32,101 women each year who Todd Akin and his juice and secretion-obsessed fellow Republicans want to deny the choice of ending a rape-related pregnancy.
Since this particular set of claims falls into two Republican sweet spots—anti-science and anti-abortion—I wouldn't look for this to be the last time this theory raises its head. Really, the only thing to wonder about is what charming language will be used next time.