We have over a dozen methods of contraception for women: pills, patches, IUDs, shots, sponges, rings, etc. 我们有数十种女性避孕手段：避孕药、避孕贴、节育环、避孕针、避孕海绵、阴道环等等。

For men, we've had the same two options for more than a hundred years: condoms and vasectomy. 可对于男性，我们一百多年来都只有两种选择：避孕套和输精管结扎术。

Despite having only two options, both of which have significant drawbacks, 尽管只有两种选择，且两者都有重大缺陷，

men currently account for 30 percent of all contraceptive use, 在所有使用避孕措施的人群中，男性目前占了30%，

with 10 percent of couples relying on vasectomy and 20 percent of couples using condoms. 其中10%的伴侣用的是结扎术，20%用的是避孕套。

Why are 20 percent of couples relying on condoms for contraception when condoms have a one-year failure rate of over 15 percent? 为什么20%的情侣会依赖避孕套来避免怀孕，尽管避孕套一年内的失败率超过了15%？

It's because many women can't either safely take currently available female contraceptives, for reasons such as blood clots, 这是因为很多女性要么由于血液凝结等原因，无法安全的使用目前提供的女性避孕措施，

or they can't tolerate the side effects. 要么是因为她们无法承受副作用。

So if we think a male contraceptive would be useful, the next question is: How do we go about developing one? 那么如果我们觉得让男性避孕会很有效，那下一个问题就是：我们该如何研发出这样一种措施呢？

Well, there's two general approaches. 有两种大体的方向。

The first approach is to try and interfere with the way the sperm swim towards or bind to the egg. 第一种办法是尝试干扰精子移动并与卵子结合的方式。

This approach turns out to be really difficult, 事实上这个办法难度相当高，

because it's hard to get enough medication in the small volume of the ejaculate 因为射出的精液容量很小，很难让足量的药物溶在里面，

and have it still work inside the female reproductive tract. 并且还能在女性的生殖道里工作。

This is why there's been a lot more work done on the second approach, which is turning off sperm production entirely. 这就是为什么更多的研究集中在第二种方式：即直接停止精子的产生。

This is also challenging. Why? Turns out that men make a lot of sperm. 不过这个方法也很有挑战性。为什么？因为你会发现男性能生产很多精子。