Rape can make you pregnant. Period.

Editor's note: Dr. Aaron E. Carroll is an associate professor of pediatrics at the Indiana University School of Medicine and the director of the university's Center for Health Policy and Professionalism Research. He blogs about health policy at The Incidental Economist and tweets at @aaronecarroll.

(CNN) -- Rep. Todd Akin made news this weekend by announcing that pregnancy from "legitimate rape" is rare. He further argued that physicians had told him that women who were traumatized in such a way had biological things happen in their bodies to "shut down" the "whole thing" so that fertilization won't occur.

There's so much wrong here that it's hard to know where to begin.

Let's start with the basics. The human body is intricately designed and exquisitely evolved to make procreation possible. In fact, some would argue that it's our primary purpose. So you have to understand that everything about our biology is there to make it easier, not harder, for a woman to get pregnant. Women can get pregnant if intercourse happens under water. Women can get pregnant from sex in any position. Women can get pregnant even when they think that they can't get pregnant due to menstruation. If you put sperm near egg, women can get pregnant.

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Aaron Carroll

There is nothing at all about a woman's mindset that affects this. Women can't wish pregnancy away. If they could, then many teen pregnancies wouldn't occur; few teens want to get pregnant. But think of the larger picture. Women in abusive relationships get pregnant. Women in horrible socioeconomic conditions get pregnant. And, yes, women who have been raped get pregnant.

The body doesn't differentiate between "legitimate" rape and "illegitimate" rape -- whatever that is. The body doesn't know whether the rapist is known to a victim. The body doesn't know if a knife or a gun, or alcohol or drugs (or any combination of them), were used.

Every sexual encounter does not lead to pregnancy, but every sexual encounter leads to the possibility of pregnancy. Period.

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So why would someone say such a thing? While it's hard to get into the mind of another individual, we can guess. This line of reasoning isn't new. It's been used for the most part to delegitimize the idea that exceptions to abortion prohibitions should exist for rape. After all, if you really believe that abortion is the taking of a human life, then it's hard to suggest that there is any rationalization for it at all. While ethically consistent, this belief is rare in the United States. Even among those who oppose abortion, most people support exceptions for rape and incest.

It's hard for a politician who firmly opposes abortion to square this. Such a person wants the support of a majority of people but doesn't want to compromise principles. One option, then, is to find a way to make the occurrence of the problem nonexistent. If pregnancy from rape doesn't happen, then we don't need exceptions in the law.

The problem, of course, is that such pregnancies do occur. More than 31,000 of them happen in America every year. Pretending they don't by listening to a few anecdotes won't make them go away.

This is what happens when reality gets in the way of our moral convictions. Life is tricky. It's nuanced and complicated and often fraught with contradictions. Contrary to what you read, most people don't have black and white views of abortion. Few believe that it should be prohibited when it might save the life of a mother. Few believe that it should be allowed a week before a fetus is full-term. In other words, relatively few people believe abortion should never be legal, and few believe it should always be legal.

This places abortion in the gray zone. That doesn't work well for elections. It also doesn't make for clean philosophical discussions. It certainly doesn't make for good sound bites.

A further problem with proclamations like Akin's, though, is what they sound like to women who have been raped. If you believe what he does, then anyone who did get pregnant wasn't "legitimately" raped. Moreover, it belies a willful ignorance of science. Rape has occurred in history time and time again. Women get pregnant from it. This is known. There is no debate to be had.

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Those who support Republicans, and even Akin, in this election believe this to be a distraction and a problem. They're right. History shows that statements like this can turn close elections. A win in Missouri for the Democrats may mean that they retain control of the Senate. Moreover, this will be what we are talking about this week instead of the economy, jobs, or health care reform. That's bad for Romney and Ryan.

The good news is that all of this is avoidable. Stick to science. If people did that more, they wouldn't have to claim they "misspoke" later.

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The opinions expressed in this commentary are solely those of Aaron Carroll.