How Often Does Rape Lead to Pregnancy?

In the event that Rep. Todd Akin's comments yesterday speak to a wider-spread misunderstanding -- that women rarely become pregnant after rape -- some may benefit from them as a learning opportunity.

[Jeff Roberson / AP]

Senatorial nominee from Missouri Todd Akin made televised remarks yesterday that included the assertion:

...from what I understand from doctors [pregnancy after rape] is really rare. If it's a legitimate rape, the female body has ways to try and shut that whole thing down.

It's unclear how common this and similar misconceptions may be, or to what extent they realistically influence productive conversation. Federal Judge Leon Holmes has been quoted in the past:

Concern for rape victims is a red herring, because conceptions from rape occur with approximately the same frequency as snowfall in Miami.

In light of the pervasiveness of the abortion conversation, it's worth reviewing what we know about this aspect of reproductive physiology.

From a holistic perspective, one might hypothesize that a woman's body could respond to the extreme stress and trauma of enduring rape in such a way that she would be physiologically more likely to miscarry (or not to conceive at all). There is a multi-million dollar alternative reproductive health market aimed at optimizing an environment for conception -- sexual positions, foods, colors, aromas, feng shui -- so there could be something to a theory that the other, much darker end of that spectrum functions analogously.

But that doesn't hold, to any relevant degree. A widely-cited 1996 study from the American Journal of Obstetrics and Gynecology sampled over 4,000 women and found that the rape-related pregnancy rate was 5.0 percent. That is, after being raped once, a woman had a 5.0 percent chance of pregnancy. That number includes rapes in which condoms were used. Small studies from other countries have reported the percentage to be much greater.

The AJOG called their finding "a significant frequency." Whether or not that percentage varies somewhat from the pregnancy likelihood in consensual sex is rendered moot by the fact that the study reported a total of 32,101 cases of rape-related pregnancy over the course of the year (in the United States alone). While specific numbers are contested, there is similarly overwhelming evidence of rape-related pregnancy by the tens of thousands in places like Rwanda where there was mass rape in the course of genocide.

Though it should not factor into treatment and discussion of post-coital contraceptives, a 1998 study in Contraception quantified a woman's average risk of pregnancy after unprotected sex as such:

• 3 days prior to ovulation: 15% chance of pregnancy
• 1-2 days prior to ovulation: 30% chance of pregnancy
• Within 24 hours of ovulation: 12% chance of pregnancy
• 1-2 days after ovulation: Around 0% chance of pregnancy

No distinction is made as to the consensual nature of the sex. But again, rape victims in hospitals are treated without regard to the phase of their menstrual cycle, and those numbers shouldn't deter anyone from seeking care.

As pervasive as abortion conversation is, it's important that we're all on the same page about reproductive physiology. How common is this belief that rape rarely leads to pregnancy? If people are earnestly advancing a cause that mistakenly overlooks 32,000 annual rape-related pregnancies, Akin's remarks calling this to light may have an upside.