- As the birth control pill turns 50 this month, scientists are still working on the elusive male pill.
- New studies suggest that male hormonal contraceptives can work, and many men would like the option.
- Some major hurdles remain.
The birth control pill turns 50 this month. And yet, even though scientists have been working on a male version for just as long, there's still no pill for men. So, what's the hold-up?
"Men make 1,000 sperm every second," said John Amory, a male reproductive specialist at the University of Washington, Seattle. "It's proven to be a lot more difficult to turn that degree of production off compared to one egg a month."
Despite the challenges, experts say that men are closer than ever to having the option of a hormonal contraceptive.
"We know it works," said Christina Wang, a male reproductive biologist at the Harbor-UCLA Medical Center and Los Angeles Biomedical Research Institute. "We just need support to make sure it gets to market so people can use it."
When the birth control pill gained FDA-approval in May 1960, it offered a whole new level of reproductive control and freedom for women. With some combination of the hormones estrogen and progestin, the pill works by shutting down signals from the brain that tell the ovaries to release eggs. Without ovulation, pregnancy can't happen.
A male hormonal contraceptive, when it becomes available, will operate in much the same way: using testosterone and probably progestin to stop the testes from making sperm.
It's a big job. A single ejaculation contains between 100 million and 500 million tiny swimmers. Already, trials have produced promising results.
In one of the largest and most recent studies, published last year in the Journal of Clinincal Endocrinology & Metabolism, more than 1,000 Chinese men received testosterone injections every eight weeks for two and a half years. The shots, results found, were more than 95 percent effective at preventing pregnancy -- close to the real-world success rate of the female pill.
Other studies have found that men completely resume sperm production a few months after they stop taking the hormones. Now, both the World Health Organization and the National Institutes of Health are supporting yet more trials.
Most likely, the male pill will not be a pill, at least not at first, because testosterone breaks down quickly in the body when administered orally. Instead, the first generation of male hormonal contraceptives might take the form of injections given at a doctor's office every two or three months; gels that men smear on their arms or stomachs every day; or long-lasting implants that would be inserted under the skin.
Amory is working on a pill that releases testosterone slowly enough to work, and his formulation is currently undergoing early-phase testing. Further off are non-hormonal medications that bind to hormone receptors and affect sperm numbers or sperm behavior.
Some significant challenges remain. For starters, hormones fail to adequately suppress sperm production in up to 20 percent of men, and scientists have no way of knowing which men will fall into that group.
There are also side effects, including acne, weight gain and a 10 percent drop in good cholesterol levels, as well as a shrinking of the testes by 25 percent -- which, Amory insisted, men don't usually notice.
Surveys suggest that about half of men would be interested in taking a hormonal contraceptive. And while women say they wouldn't trust most men to take their medication, most say they trust their own partners.
For a male version of the pill to reach the market, pharmaceutical companies will need to take a bigger interest in making it happen. By expanding the toolbox of family planning choices, experts hope that male hormonal contraceptives will help prevent some of the millions of unintended pregnancies that happen every year.
"Men are often interested in having sex and not being fathers," Amory said. "If they had an option, I think many of them would embrace it."