When I tell people that I'm trying to develop a contraceptive pill for men, the response usually varies along gender lines.
当我跟别人说我正在尝试研发男性避孕药时，对方的反应一般取决于性别。
Women say something like, "Fantastic. It's about time. When?"
女性会说，“太好了，是时候了。什么时候（能研制出来）啊？”
Men have one of two responses.
男性一般会有两种反应。
They either love the idea, or they look at me a little warily and wonder what exactly I have in store for their testicles.
他们要么很喜欢这个想法，要么就会用警惕的眼神看着我，在想我到底打算对他们的睾丸做些什么。
So why does the world need a male pill?
那么，这个世界为什么需要男性避孕药？
Well, what if I told you that of the six million pregnancies annually in the United States, three million of them are unintended?
如果我告诉你美国每年六百万的怀孕人口中，有三百万都是意外怀孕的呢？
That's half. That's a really surprising number.
也就是一半。这是一个很让人惊讶的数字。
And those three million unintended pregnancies
而这三百万计划之外的怀孕
account for the vast majority of the more than one million abortions annually performed in the United States.
很大程度导致了美国每年一百多万次的堕胎。
Happily, the rate of unintended pregnancy has fallen in the last few years by about 10 percent.
令人欣慰的是，最近一些年，意外怀孕的比例已下降了10%左右。
This is because more women are using effective, long-acting, reversible forms of contraception.
这是因为更多的女性在使用有效、长效、可恢复的避孕方式。
But we still have a long way to go.
但我们还有很长的路要走。
One approach that's finally becoming a real possibility is better contraceptive options for men. Think about it.
一种即将成为现实的办法是针对男性的更好的避孕措施。想想吧。
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,
这是因为很多女性无法安全的使用目前提供的女性避孕措施，
for reasons such as blood clots, or they can't tolerate the side effects.
要么由于血液凝结等原因，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。
Men make a thousand sperm every second
每秒中，男性可生产出一千个精子，
and to have an effective contraceptive, you need to get that level of sperm production down to one percent of its normal value.
所以有效的避孕药必须把这个精子生产率降到正常值的1%。
The good news is, this is possible, almost. The most studied approach has been to use hormones to suppress sperm production.
好消息是，这是可以做到的，几乎可以。被研究最多的方法是用激素抑制精子生产。
Testosterone and progesterone, when administered together,
睾丸酮和黄体酮，当一起被服用的时候，
will suppress the signals from the brain to the testes to make sperm,
会抑制大脑发射的让睾丸生产精子的信号，
and in about 90 percent of men, sperm production after three to four months will stop.
在90%左右的男性中，这个方法能使精子的产生在三四个月后停止。
Unfortunately, 10 percent of men don't respond to these hormonal regimens for reasons that aren't understood.
不过很遗憾，还有10%的男性不会对这些激素疗法做出反应，原因我们目前还不了解。
For the last several years, my colleagues and I have been taking a different approach to male contraceptive development,
过去几年里，我和我的同事采用了另一种解决男性避孕问题的方法，
one that doesn't involve the administration of hormones.
一个不需要激素疗程的方法。
Specifically, we are looking to block the function of vitamin A in the testes. Why?
具体来说，我们在研究如何阻止睾丸中维生素A的活动。为什么这么做呢？
Well, for over 90 years it's been known that you need vitamin A to make sperm.
90多年来，我们一直都知道你需要维生素A来生产精子。
Animals who are deprived of vitamin A in their diet stop making sperm and restart making sperm again when the vitamin A is reintroduced.
饮食中缺乏维生素A的动物会停止生产精子，当维生素A被重新引进饮食后，它们又会重新开始精子的生产。
The vitamin A that we ingest is converted by a family of enzymes to something called retinoic acid.
我们摄入的维生素A会被一个类别的酶转化成视黄酸。
One of these enzymes is found only in the testes. It's this enzyme that we are attempting to block.
其中一种酶只在睾丸才有。我们试图限制的就是这种酶。
The blockade of this enzyme should deprive the testes of retinoic acid
阻断这个酶应该可以使精子丧失视黄酸，
and stop sperm production without affecting vitamin A's functions elsewhere in the body.
从而停止精子生产，同时并不影响维生素A在身体其他部分的功能。
We're testing this approach in animals and hope to move to human testing soon.
我们正在动物体内测试这个方法，希望不久后可以在人体内测试。
Obviously, the impact of such a male contraceptive would go well beyond reproductive biology.
当然了，这样的男性避孕药影响的肯定不只是生殖生物学。
It's interesting to speculate about the effect that it would have on relationships between men and women.
它会如何影响男性与女性的关系也是个有意思的题目。
One intriguing possibility is that a man could monitor his contraceptive status over time.
一个有趣的可能性是男性可以随时监测自己的避孕状态。
In the last several years, two groups have introduced home sperm-testing devices that are iPhone-based and that are easy to use.
在过去的几年里，两组人员引入了家用的精子测量设备，这些设备基于iPhone，并且很容易使用。
A man could test his sperm count and share the result with his partner.
男性可以测量自己的精子数量，并把结果分享给自己的伴侣。
If the man's sperm count were zero, the man and his partner would feel very comfortable relying on his contraceptive.
如果他的精子量为零，那他和他的伴侣就可以很安心的依靠他的避孕药避孕。
A tool like this, coupled with a male contraceptive, could greatly increase the role for men in preventing unintended pregnancy.
像这样的工具，加上男性避孕药，可以大大增加男性在预防意外怀孕中的作用。
The researchers who are working on male contraception are trying to create a better future for couples,
研发男性避孕药的研究人员正在尝试为伴侣创建更美好的未来，
a future where contraception is no longer considered just "a woman's issue," rather an issue for couples to decide together.
一个避孕不再只是“女性的问题”，而是由伴侣双方一起决定的未来。
So why does the world need a male pill?
所以说，为什么世界需要男性避孕药？
Well, I believe that a male pill will help reduce the stubbornly high rates of unintended pregnancy and abortion
因为我相信男性避孕药可以帮助降低总是居高不下的意外怀孕和堕胎的比率，
and allow men to equally participate in contraception. Thank you.
让男性可以平等的参与避孕。谢谢！