Not every man wants to be a father and not every father wants more kids. Roughly half of all pregnancies in the United States are unintended. But when it comes to male birth control, none of the options are ideal. Men can rely on their partners to use female contraception, which places an undue burden on women and limits male agency. They can use condoms, which aren’t always effective at preventing pregnancy and can make sex less pleasurable. Or they can, often irreversibly, prevent reproduction with vasectomies. That’s more or less it. The dream of a great male birth control solution has lived for decades as more or less just that: a dream.
Reversible, reliable, safe. Pill, injection, non-surgical procedure. Until recently, these goals have seemed uniformly out of reach. But researchers just unveiled a promising new male oral contraceptive at the Endocrine Society’s annual meeting in New Orleans. The pill, called 11-beta-MNTDC, ostensibly prevents fertility with progestin while keeping libido up with testosterone. It is far from pharmacy shelves and may never make it through the rigorous FDA approval process, but 11-beta is as far as we’ve come on male birth control to date.
“Safe, reversible hormonal male contraception should be available in about 10 years,” wrote study coauthor Christina Wang of the Los Angeles Biomed Research Institute in a statement announcing progress on the pill. “The goal is to find the compound that has the fewest side effects and is the most effective.”
But why has it taken this long? Why is there another decade to go? What barriers to male birth control still exist, what new interventions are on the horizon, and how exactly would they work? Here’s what we know so far.
Condoms Are Not Enough
Men can do their part to prevent these unwanted pregnancies by either getting vasectomies or using condoms, but neither contraceptive is ideal, from a public health perspective. Vasectomies are effective but usually irreversible and can be prohibitively expensive. Condoms are the backup, but they are only 83 percent effective at preventing pregnancy (higher when used perfectly, though few manage that) and men, frustrated by the lack of sensation or allergic to the ingredients, often opt out—a strategy that can lead to some surprises down the road.
So the burden of preventing pregnancy falls largely upon women who (despite legislative attempts to erect barriers) can usually access hormonal contraceptives. But many men recognize that this is not ideal, for either gender. “Just as women should have the reproductive right to decide if or when to have children, men should similarly be able to control their fertility and reproductive outcomes,” Harvard University’s Olivia Plana wrote in a 2017 review article in the American Journal of Men’s Health.
Men tend to agree. One 2012 study found that 78 percent of men believe that both genders should share equal responsibility for decisions about contraception. In 2005, more than half of men in stable relationships told researchers they would be enthusiastic about trying hormonal male contraceptives, as long as the effects were reversible. When it comes to a male birth control pill, or a non-surgical, reversible vasectomy, the world is ready. Science—and society—may not be.
Scientific Barriers To Male Birth Control
Female birth control is about preventing the fertilization of one ovum, primed for procreation once per month. That’s it. Male birth control requires wrangling millions of sperm produced constantly and en masse. And the complication is compounded by the means of measurement. When measuring whether birth control succeeds or fails in women, we need only look at the woman: pregnancy is a failure, lack of pregnancy is a success. In men, we need to examine partners to figure out whether the treatment worked.
“Females only ovulate once per month, so it’s relatively easy to block with an endocrine approach,” Michael K. Skinner, director of the Center for Reproductive Biology at Washington State University told Fatherly. “Males produce millions of sperm daily…it’s difficult to design endocrine approach without shutting down all of male endocrinology.” In other words, in order to impact sperm production meaningfully, hormonal therapy would need to all but shutter the endocrine system—with serious side effects.
Even when researchers manage to discover a therapy that covers all of these bases and accounts for these challenges, it remains difficult to design experiments that test the efficacy of any male contraceptive. Because there is a simple procedure for testing female contraceptives. Not so for male birth control.
“There’s a pipeline for female methods. It includes about 20,000 [menstrual] cycles of research demonstrating safety in women, along with efficacy,” said Diana Blithe, program director for the Male Contraceptive Development Program at the National Institutes of Health, at a 2017 conference. “The road to a male contraceptive is less straightforward. It’s unclear how many subjects and how long [the experiment would have to run for]. They don’t have cycles.”
From a drug approval perspective, male birth control also needs to be designed to have virtually no side effects, because the FDA will usually only overlook the side effects of a drug when those downsides do not exceed the discomfort or risk of the disease being treated. If a new medication causes suicidal ideation but cures the common cold, it won’t pass muster—if it treats deadly cancer, it just might. Because contraceptives do not treat a disease in the first place, researchers need to ensure that candidate drugs for both men and women have no serious side effects. For male birth control, the bar is even higher. Because women are at least at some increased risk when they become pregnant, and side effects to a drug that prevents that risk may be considered acceptable. Impregnating a woman, on the other hand, comes with no particular risks for men. A drug that prevents this would have to have essentially no drawbacks.
The Social Barriers To Male Birth Control
Even if researchers climbed over those scientific mountains, there would be social barriers to contend with. Funding is, as ever, a problem. “Low levels of government funding for the topic is one of the issues,” Skinner says. “The federal government has had budget reductions at NIH, so they have not been able to support this area well.” The industry has failed to step up and provide the funds that the government will not. “While in the early 2000s, there was promising research in the field, the organizations performing it were bought up by larger groups, and the research dropped,” Sam Jackson, medical researcher at the digital health company Medzino, told Fatherly. “Male contraceptive research has been starved of funding.”
Pharmaceutical companies and the U.S. government alike stepped away from funding male birth control due to the suspicion that men would not use it. This suspicion has been proven false across multiple studies—men consistently tell researchers that they want hormonal birth control—but the reticence to fund a project men might not use lives on. “The thought was that males would not take pill or contraceptive,” Skinner says. “But more recent studies of the last ten years have suggested this is no longer a problem.”
At this point, experts agree, the social barriers to male birth control are less the product of active resistance or disinterest from men and more the fault of an unenthusiastic government and industry. “Social responsibility by males is not a major block,” Skinner says. “There’s still some church opposition that impacts private foundation funding in the area, but this also not major issue. It is lack of funding.”
Is Male Birth Control On The Horizon?
The most promising avenue of research for male birth control is hormonal therapy—in other words, a true male birth control pill. Experts working on a male pill take advantage of the fact that hormones such as progestin can indirectly decrease testosterone levels. Specifically, progestin prevents the hypothalamus from making Gonadotropin-releasing hormone (GnRH), which in turns inhibits the pituitary gland from making Luteinizing hormone (LH), the hormone that prompts cells in the testis to produce testosterone.
The good news is that testis have testosterone to spare—the cells that produce sperm in the testis can contain up to 100 times more testosterone than the rest of the body. The bad news is that seriously reducing testosterone comes with a battery of unpleasant side effects, from loss of muscle mass to loss of sexual desire. The solution? “We add back testosterone, enough to restore libido and muscle mass, but not enough in the testis to make spermatogenesis,” Blithe says.
Early attempts at balancing testosterone and progestin failed, mainly because there is no easy way to deliver an oral dose of testosterone that can counter the progestin. Testosterone leaves the blood far too quickly, requiring multiple doses per day, and attempts to create a longer-acting androgen were so potent that they caused liver toxicity in animal studies. Progestin topical gels, administered to patients’ shoulders alongside testosterone gels have shown some promise, and a trial of 420 couples in America, Europe, and Africa is currently underway. “This potentially inhibits sperm development, without the hormonal suckerpunch,” Jackson says.
A more appealing solution, which came into its own with the results presented at the Endocrine Society, is a custom, composite molecule—a sort of testosterone-progestin, supplemented with chemical groups called aldehydes that keep it in the bloodstream longer. “Our results suggest that this pill, which combines two hormonal activities in one, will decrease sperm production while preserving libido,” Wang said in the press release. Successful Phase I trials are far from definitive but, so far, the drug appears to be safe and effective.
What About a Reversible Vasectomy?
The past decade has brought us another, non-hormonal option, known as vas occlusion. It is essentially a reversible vasectomy. The idea is that a polymer substance could be injected into the vas deferens, the tube that carries sperm to the ejaculatory duct, blocking the sperm from entering the ejaculate. It would function in the same way as a vasectomy—sperm production would continue unfettered, never arriving in the semen—but it would be reversible. The polymer could be flushed out of the vas with a second injection.
“This technique blocks the movement of sperm through the vas deferens,” Jackson says. “This means that semen will be just that: semen, but without any sperm.”
The most promising of these therapies is Echo-VR, Jackson says, and clinical trials are due to begin in 2020.
So How Far Are We From Male Birth Control, Really?
There are other potential therapies on the horizon. There’s JQ1, a compound that inhibits cancer cell growth and may also prevent spermatogenesis in the testis; there’s Lupeol, a cancer drug that inhibits the calcium channels of sperm cells, making it impossible for them to enter the egg; there’s WIN 18,446, a compound that blocks testicular synthesis of retinoic acid, which is needed for sperm production (but cannot be taken with alcohol).
Which is to say, there’s no shortage of ideas or researchers willing to try them. And it is possible that Wang is right—perhaps we are a mere decade from a male birth control pill, or truly reversible vasectomy. But between funding barriers and the simple scientific difficulty of getting a drug that is safe and effective through clinical trials, Skinner suspects that even a deadline one decade from now may be overly optimistic.
“I am not aware of anything that will be available soon that has shown effective male contraceptive,” Skinner says. “What is needed is a long-acting reversible contraceptive. But without sufficient research support for the scientists, we are not likely to see it soon.”