Experts: Rape does not lower odds of pregnancy

The science behind Akin's rape comments

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Story highlights

  • "If it's a legitimate rape, the female body has ways to try and shut that whole thing down," Akin says
  • Experts dispute the GOP Senate candidate's view
  • Chronic stress can decrease fertility, but not the acute stress of rape, says professor

A woman's chances of becoming pregnant are the same after rape as they are after consensual sex, according to medical experts and published studies.

Their conclusion contradicts a statement made last weekend by Rep. Todd Akin, R-Missouri, who suggested in an interview with CNN affiliate KTVI that rape rarely results in pregnancy.

"From what I understand from doctors, that's really rare," said the U.S. Senate candidate in response to a question about whether abortion should be legal in cases of rape. "If it's a legitimate rape, the female body has ways to try and shut that whole thing down."

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Akin's supporters say he was given misinformation that appears to stem from a 1999 article by Dr. John C. Willke, the former president of the National Right to Life Committee.

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Willke wrote that rape pregnancies are "extremely rare" and that the stress of rape helps prevent pregnancy.

"To get and stay pregnant a woman's body must produce a very sophisticated mix of hormones," Willke wrote in a 1999 article published in "Life Issues Connector," an anti-abortion newsletter. "Hormone production is controlled by a part of the brain that is easily influenced by emotions. There's no greater emotional trauma that can be experienced by a woman than an assault rape. This can radically upset her possibility of ovulation, fertilization, implantation and even nurturing of a pregnancy."

Willke, who is in his late 80s and lives in Cincinnati, did not return a call from CNN.

But scientific data support neither Willke's assertion nor Akin's statements, according to experts.

"What we know is that chronic stress can decrease fertility," said Dr. Sharon Phelan, a fellow at the American Congress of Obstetricians and Gynecologists (ACOG) and professor in the Department of Obstetrics and Gynecology at the University of New Mexico, in a telephone interview with CNN.

Phelan cites emotional, medical or nutritional stress as forms of chronic stress.

"The acute stress does not have the same impact," she added, referring to the act of rape.

A 1996 study published in the American Journal of Obstetrics & Gynecology estimated 32,101 pregnancies in the United States each year result from rape.

Opinion: Rape can make you pregnant. Period.

Generally, a single act of a rape has about a 5% chance of resulting in pregnancy among victims aged 12 to 45 who are not on birth control, according to ACOG figures. But experts say that percentage fluctuates greatly, depending on a woman's ovulation cycle at the time of intercourse.

Three days prior to ovulation, a woman has a 15% chance of pregnancy after a sexual encounter; one to two days prior to ovulation, the odds double to 30%; they plummet to 12% on the day of ovulation, Phelan said.

"Since a rape would likely happen at any point in the cycle, the overall risk -- without considering day of cycle -- would be close to a 16% chance of occurring on a fertile day and then there is, at maximum, a 30% chance of conception," Phelan said.

While the stress associated with rape may not lower a victim's risk of becoming pregnant, rapists often do not ejaculate, thereby decreasing their victims' risk of pregnancy, said Phelan.

Akin has apologized for his remarks.

"I had heard one time a medical report that it's hard to get, it's harder for somebody to get pregnant under those conditions," he told radio host Sean Hannity on Monday. "I don't believe that's true now. In fact, I've checked the facts and that's wrong. I was just wrong in that statement."

Akin asks for 'forgiveness' in new TV ad

Dr. David Grimes, a clinical professor in the Department of Obstetrics and Gynecology at the University of North Carolina School of Medicine, said he was shocked when he heard Akin's original remarks.

"That's part of the broad theme here of misogyny -- that women are responsible for being raped; they brought it on themselves through their provocative behavior or clothing," Grimes told "AC360" on Tuesday night. "Then, on top of that, should they be raped -- and if they get pregnant -- that, too, is their fault. It's a double whammy. It's cruel beyond words."

Grimes rejected the authority of Willke, a general practitioner, to make such statements. "He has no scientific credentials," said Grimes, who serves on the editorial boards of several publications, including Obstetrics and Gynecology, Obstetrical and Gynecological Survey and the journal Contraception.

"In medicine, opinions count only to the extent that they're borne out or supported by evidence. No evidence at all supports Dr. Willke's bizarre theories."

Opinion: Wake up -- It's not just Akin

Surviving sexual assault: Share your testimony on CNN iReport.

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