AUDIE CORNISH, HOST:
There are about a half-dozen different birth control options out there for women. For men, not so much, so how come? Well, a new drug looked promising - an injection of hormones that was 96 percent effective - but researchers had to end the study early after the men reported too many side effects. The findings were published last week in The Journal of Clinical Endocrinology and Metabolism. NPR's Rob Stein is here to talk with me about it. Hey, there, Rob.
ROB STEIN, BYLINE: Hey.
CORNISH: So tell us more about this study. How did it work?
STEIN: So this was a pretty big study. It was sponsored by the World Health Organization. And they gave shots every eight weeks to 320 men in countries around the world. As you mentioned, the shot contained two hormones, and it worked pretty well. It knocked down these guys' sperm counts really significantly and prevented pregnancies really well. There was only a handful of pregnancies among these men.
The problem was there were two committees that were paying really close attention to this study, and they started to realize that a lot of guys started dropping out because they're experiencing side effects. The most common side effect was acne. In some cases, it got pretty severe. Some men also develop mood swings, and in some cases, those mood swings got pretty bad. One guy developed a pretty severe case of depression. Another guy actually tried to commit suicide. So because of that, they cut the study short.
CORNISH: Even though most of the men said they would still take this contraceptive if it was available commercially.
STEIN: Yeah, when they asked the guys in the study who didn't drop out, you know, most of them did not experience severe side effects. And so they said, yeah, if this was available, they would use it.
CORNISH: But there's been so much eye rolling on the Internet about these side effects - right? - mood swings, depression, weight gain - because these are things women experience with hormonal birth control.
STEIN: Yeah, right, and so no birth control's perfect. Almost everything has some sort of side effect. And the side effects from this study were, you know, not that out of whack with what you see in other kinds of birth control, except for the severe emotional problem. So that was definitely more than you would see for, say, the birth control pill.
Also, you have to remember that there's a little bit of a different risk-benefit analysis when it comes to men using a contraceptive. When women use a contraceptive, they're balancing the risks of that against the risks of pregnancy, and pregnancy itself does carry some risks. In the case of men, these are healthy men, and they're not going to suffer any risks if they get somebody else pregnant.
CORNISH: So why is it so hard to develop birth control for a man? What's going on with that industry?
STEIN: Yeah, that's the big question. I mean, you think - we've had the pill for women for decades, so why has it taken so long to come up with something for men that's better than a condom or a So there are a couple of reasons. One is it is harder from a biological point of view - just the numbers game. Think about it. Women produce one egg a month. Men are producing millions of sperm constantly. Women - you can sort of take advantage of their normal monthly cycle - kind of take control of that with a birth control pill. There's nothing equivalent to that in men.
CORNISH: So what does this mean for male birth control in general? I mean, is this particular study a setback or no big deal?
STEIN: Well, yeah, it is a setback. It's definitely a disappointment. People had a lot of optimism about this study. They thought that this could be a really effective approach. But I've talked to a bunch of scientists about this, and they're saying, look, we're not giving up yet. They're going to tinker with the doses in the hormones that they gave men in this case, and they think they might be come up with safer levels of the hormones. They're also going to try different kinds of hormones, maybe administering it definitely, like a gel, for example, or maybe an implant or something like that.
There are also other targets that they could go after to try to make sperm not work as well, like make the sperm not swim as well or not be as good at fertilizing the egg. So there is a lot of research going on still, but most of the other research is at a fairly early level. So scientists are saying, you know, we're going to keep trying, but we're probably at least a decade away from coming up with something new for men.
CORNISH: That's NPR's Rob Stein. Rob, thanks so much.
STEIN: Oh, sure. Nice to be here.
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