98 percent of American women have done it.

37 million Americans are currently doing it.

Most of the GOP candidates oppose it.

What is it?

If you said "sex," you were close. The answer is "use contraception." In recent weeks, the GOP candidates have been asked a lot about their views on abortion but not one has been asked his position on contraception (or even prevention in general). Really big oversight. Maybe its because everyone just assumes they all support contraception. After all, who doesn't?

If their statements and actions are indicators, most of the GOP candidates oppose contraception. Mitt Romney, Mike Huckabee, Ron Paul, Tom Tancredo, Duncan Hunter, and Fred Thompson all define life as beginning at conception or fertilization, in other words when sperm meets egg. (It's worth noting that there's no medical way of knowing when sperm meets egg. According to the American College of Obstetricians and Gynecologists, a fertilized egg isn't even considered a pregnancy.) This "life at fertilization" assertion is what is called in the business "dog whistle" politics: a political message only a specific constituency can hear. The reason, of course, to keep the message on one frequency, is that in most cases the issue is deeply unpopular with most of the American people. The candidate's whistle, in this case, is a pledge to support the anti-abortion movement's campaigns to roll back access to contraception.

If a candidate pledges to define life as beginning at fertilization, then anything that prevents implantation will end a life. And pro-lifers insist the pill does that. Birth control then becomes abortion, and as we know, abortion gets banned. Why hasn't the media sunk its teeth into this little curiosity? At the very least, it would make for some really great TV. Someone needs to ask any of the GOP candidates (except Guiliani) whether he supports access to birth control. 91 percent of the American public (the majority of the pro-life public included) does so strongly.

Along with pledging to give a fertilized egg full constitutional rights candidates prove their anti-contraception credentials in other ways. McCain boasts that he has consistently voted against funding pregnancy prevention for poor women. Romney vetoed an emergency contraception bill, calling it an 'abortion' drug. Ron Paul opposes federal funding for any contraceptive service.

These guys may try to outdo each other on anti-abortion rhetoric and explain, unflinchingly, how doctors will be thrown in jail when Roe fails (an inevitability in their minds). But it's the contraception question that really scares them. Because once the presidential debate focuses on how the candidates plan to alter the average American's sex life (made possible thanks to family planning) it is lifted from the pink ghetto of "woman's issues" and becomes a concern of male voters too.

Study after study proves that contraceptive use is the only way to prevent abortion; the places on earth contraception is most available are also where abortion is most rare. According to Save the Children, the countries where infant and maternal mortality are the lowest is where contraception is used the most (because planned pregnancies are healthier pregnancies.) Using abortion rates, maternal and infant death rates, as measures, it's undeniable: the most pro-life thing a president can do is support the right to use contraception and make it widely available. The public knows this. And sometime before the primaries the candidates must be made to state openly whether they support contraception. Because the candidates know those professional pro-life dogs are still listening for the right whistle.

This piece was originally published on the Huffington Post.