For many couples, contraception is the woman’s responsibility.

Most of my friends would say that it’s because women are more responsible, but they would also say that it’s because there are a greater number of easily manageable, effective and reversible options available to women (pills, patches, shots, vaginal rings, IUDs, etc.) than there are to men, who can rely on only condoms or vasectomy. (Of course, some men think that they can rely on withdrawal—ha!)

That’s why I found a recent study on a new male contraceptive so fascinating.

Researchers are developing a new gel for men and have found that it creates a “very low sperm count” (fewer than one million sperm per milliliter)—a count that’s low enough for pregnancy to be considered extremely unlikely—in 89% of men.

How does that sound to you?

TWO HORMONES STOP SPERM IN ITS TRACKS

I’m sure you’re wondering how effective this gel would be compared with popular forms of birth control, but it’s too early to know. For one thing, the 89% figure I mentioned above is considered too low for real-life use—the researchers want to get that figure up to 95%, and then, they figure, the gel will be ready for real-life (meaning, real-sex) testing.

It seems almost inevitable, though, that some kind of sperm-suppressing male contraceptive is going to come out of all this. For one thing, the idea behind the new gel is surprisingly simple. When I called lead researcher Christina Wang, MD, she told me that prior studies had shown that giving men two particular hormones through injections, implants or pills would suppress sperm. The hormones are progestin (a synthetic female hormone, actually) and, surprisingly, testosterone, the hormone that makes men, well, men (more on that in a minute). But the type of progestin used was causing side effects, such as acne and increases in cholesterol levels that would have made the idea unappealing for most men.

She and her colleagues decided to see whether a new type of synthetic progestin, called Nestorone, might not only work with testosterone to reduce sperm counts but also cause fewer side effects…and whether they could apply the hormones in an easy-to-use gel form. So they performed what’s called an early “proof-of-concept” study.

Results: As hoped, the side effects were mild—only a few men developed acne, which Dr. Wang thinks might be controlled by adjusting the hormonal concentrations in the gel.

I know what you’re thinking…testosterone as birth control? Dr. Wang explained that supplementing the body with testosterone leads to the body creating less of it in the testes—and sperm doesn’t get produced unless there’s a high concentration of testosterone in the testes. Amazingly, this reduction of testosterone in the testes doesn’t decrease libido. Plus, research done with testosterone injections has shown that the body’s testosterone production kicks in again once supplementation stops, so the changes are reversible (though returning to normal sperm production can take six months or so). If any men are concerned that Nestorone, a synthetic female hormone, may have feminizing effects, they shouldn’t be, said Dr. Wang. “It’s not like estrogen, so there’s no potential for that.”

WHAT’S NEXT FOR THE GEL?

As fascinating as the study is, obviously the effectiveness of the gel needs to be improved if it’s going to become a viable contraceptive. “Somehow, not every guy using the gel suppresses testosterone, and we’re working on finding out why,” Dr. Wang said. More studies are planned.

All of this, of course, leads me to the larger question: Even if a contraceptive gel does become available for guys, would they actually use it? Dr. Wang thinks so. She mentioned surveys that have shown that about 50% of men would use a male contraceptive like this. Still, as much of a breakthrough as this is, personally, I have my doubts…because what people say that they’ll do isn’t always what they will do!

I want to know what you think. Men: Would you use a contraceptive gel that you had to apply, say, every day? Ladies: Would you trust your man to use it, or would you still use your own birth control as another layer of protection? Comment below!