Let us begin today's screed with a parental advisory:

The following column dabbles in matters of human reproduction and therefore should be kept out of reach of anyone under the age of 47. After all, Gov. Tim Pawlenty threatened to veto this year's education bill until lawmakers dropped a comprehensive sex-ed requirement. So I guess children should be allowed to discuss human reproduction only on the playground or Internet chat rooms.

Kids gone? Good. Let's begin.

Today's topic has perplexed men and women (especially the women) for years: Why do almost all health insurance plans cover prescriptions to treat erectile dysfunction while many do not cover contraceptives?

The answer is as easy as the answer to "Who's buried in Grant's Tomb?"

Because men run the world.

It is the male of the species that suffers erectile dysfunction, which, of course, means that it is a problem of Earth-shattering importance.

Impotence cannot stand!

Meanwhile, it is women -- who pay 68 percent more for health care out-of-pocket than men -- who are left to handle most of the chores when it comes to Katie barring the door.

No, it isn't fair. But it sure is hard to explain. Just ask John McCain.

The Republican candidate for president spoke to businesswomen in Hudson on Friday as part of an effort to convince women that he is their best choice.

But on Wednesday, his "Straight Talk" express stumbled on women's issues when he was asked about the disparity between insurance coverage for men and women.

McCain looked like someone had just sat on a whoopee cushion.

When a female reporter asked him the Viagra question, he first said he didn't "want to talk about that issue." Then he said he couldn't remember how he had voted on legislation to require contraceptives to be covered by insurance. (Hint: If he had voted for such a law, he would have remembered.) Then he went totally blank.

Call a physician if the appearance of being completely flummoxed persists more than four hours. Poor Johnny Mac probably would rather have discussed free trade with Baluchistan.

I don't blame him: Most men are more familiar with Baluchistan than the mechanics of contraception. One of the biggest miracles is how women pay for it.

(To see McCain's awkward answer, click on Star Tribune health reporter Josephine Marcotty's BodyTalk blog: www.startribune. com/bodytalk.)

The irony is that it was a female McCain campaign adviser, Carly Fiorina, who raised the issue: She told a group of women last Monday that the Viagra advantage for men was unfair, and that she had heard a lot of women complain about it:

"Many health insurance plans ... cover Viagra but won't cover birth control medication," the former Hewlett-Packard CEO said. "Women would like a choice."

Yes, they would. McCain says no.

For years, there has been an "EPICC" effort in Congress to help redress that imbalance with a proposal called the Equity in Prescription Insurance and Contraceptive Coverage Act. McCain has voted against it. Twice.

The intent of the legislation is to ensure affordable contraceptives to women; nearly all women rely on contraceptives at some point in their lives.

And the bill makes sense: Thirty million sexually active women run the risk of unintended pregnancies each year. Without affordable contraception, they can incur expensive healthcare needs, from routine pregnancies to C-sections, abortions and medical emergencies. Still, drugs to treat erectile dysfunction and male pattern baldness are often covered while contraceptives are not.

One absurdity: Half of large insurance plans don't cover routine contraceptive costs, but two-thirds of the medical plans pay for abortions.

"It's an outrageous inequity," says Sarah Stoesz, head of Planned Parenthood Minnesota, North Dakota, South Dakota, who points out that men run most insurance plans. "Birth control is a basic health care need for almost all women. The only reason it isn't covered is insurance companies might have to reduce benefits for men, and increase them for women.

"They don't want to do either."

Boys, boys, boys.

Didn't our mothers teach us anything? It takes two to tango, and two to make babies. And two not to.

Men, we aren't holding up our end.

And Viagra won't help.

Nick Coleman • 612-673-4400 ncoleman@startribune.com