That stems from an oft-quoted study by a guy named Mecklinberg.
Mecklenburg cited a number of factors for his theory, including that not all rapes resulted in “completed act of intercourse” and that it was “improbable” that a rape would occur within “the 1-2 days of the month in which the woman would be fertile.”
But it was Mecklenburg’s presumption that a traumatized rape victim “will not ovulate even if she is ‘scheduled’ to” that appeared to be the basis of Akin’s recent remarks.
To support his conclusion, Mecklenburg cited studies that were allegedly done at extermination camps in Nazi Germany.
Nazis reportedly tested the theory “by selecting women who were about to ovulate and sending them to the gas chambers, only to bring them back after their realistic mock-killing, to see what the effect this had on their ovulatory patterns. An extremely high percentage of these women did not ovulate,” the article said.
Newer research shows it's all bullshit, of course. But it's still part of the GOP canon; it's how Akins --- who sits on the house Science committee --- "knows" that "the female body has ways to try to shut that whole thing down.”