RAY SUAREZ: It doesn't look like much: six-feet tall, a leafy shrub growing amid the lush foliage of an Indonesian forest. But a chemical locked in these leaves could become a useful tool for limiting population growth, here in Indonesia and potentially around the globe.
To get to the plants, it's a one-hour hike, or a white-knuckled motorcycle ride up a steep mountain path and across two rickety wooden bridges.
The plant is called gandarusa and its medicinal qualities have been known to people here for centuries.
Traditionally, its leaves have been brewed into an herbal remedy for stress, something to soothe the nerves. But people have talked about an unexpected side effect: reduced male fertility.
Now researchers in Surabaya, on the eastern edge of the island of Java, are drying the leaves, chopping them up, extracting the active chemical, and putting it in capsule form to see if it works as a reliable form of male contraception.
There's growing confidence that this is a find that's eluded scientists for decades: a cheap, easy-to-make, over the counter daily birth control pill, for men.
Bambang Prajogo directs the project at Airlangga University.
BAMBANG PRAJOGO, Airlangga University: Since 1987, when we began doing research using mice, all of the testing has shown it is safe, it is effective and it has few side effects. So now we are undergoing testing in human beings.
RAY SUAREZ: Doctors are especially excited because gandarusa doesn't alter male hormones but rather changes the chemistry on the tip of each individual spermatozoon, making them unable to pierce the outer wall of a female egg, or oocyte.
Dr. Dyan Pramesti is working on the clinical trial.
DR. DYAN PRAMESTI, Airlangga University: It interferes with the enzyme which is located on the sperm head. The enzyme is needed to perforate the wall of the oocyte. If the enzyme is not active, or reduces the activity, the sperm cannot perforate the wall of the oocyte.
RAY SUAREZ: So no pregnancy?
DR. DYAN PRAMESTI: No pregnancy.
RAY SUAREZ: Dr. Pramesti and her colleagues have made another crucial finding: the pill's effect is not permanent. On average, men were fertile again just two months after they stopped taking the pill.
Bambang says the testing on just over 100 couples has shown impressive results.
BAMBANG PRAJOGO: We've done two rounds of testing on humans and so far, no pregnancies have resulted. We are now starting Phase 3 testing with 350 couples and we are hoping we will continue with our 100 percent success rate.
RAY SUAREZ: The third phase of testing isn't expected to be complete until the end of the year.
If gandarusa works, and works safely, there's still one important question. Will men use it? Today in Indonesia, fewer than two percent of men participate in contraception.
Sugiri Syarief directs the country's family planning board.
DR. SUGIRI SYARIEF, director of the Population and Family Planning Board: Mostly men say that family planning is responsibility just for woman.
RAY SUAREZ: They think that?
DR. SUGIRI SYARIEF: Yes. They think that. Family planning, oh that is the woman's responsibility. Right now we try to make awareness among the men that family planning is not only for women, but it is a decision made by couples, husbands and wives.
RAY SUAREZ: But Health Minister Endang Rahayu Sedyaningsih says the low participation rate is because right now men have only two options: using condoms or getting a vasectomy.
DR. ENDANG RAHAYU SEDYANINGSIH, Minister of Health, Indonesia: They don't like those choices. But here if we can find a pill that they can just swallow and no affect to their—
RAY SUAREZ: Desire?
DR. ENDANG RAHAYU SEDYANINGSIH: Yes (laughing). Libido. So I think they would be very happy to take that.
RAY SUAREZ: So far, none of the men in the studies have reported a diminished libido. In fact, thirty-six year old Panca Ariansyah, says he's experienced a slight increase. He's an enthusiastic supporter.
PANCA ARIANSYAH: I would recommend to my friends that they try gandarusa. It's easy and there are no side effects.
RAY SUAREZ: He and his 29-year old wife Mujiasri live in one of the poorer areas of Surabaya, where many families have four or more children. They decided to take part in the gandarusa trials because they already have three daughters and they say that's enough.
MUJIASRI: I've used birth control pills before but I still ended up getting pregnant.
RAY SUAREZ: So now it's your turn to take the pills?
RAY SUAREZ: Indonesia, with a population of 240 million people, is the world's fourth most populous country, so limiting growth has been a top priority for the government. And it’s had a fair amount of success over the last four decades, says Dr. Sugiri.
DR. SUGIRI SYARIEF: We have already changed from big family to small family right now. In 1970s our fertility rate was 5.6 children per woman. Now it is already 2.6 children per woman. It's very good in terms of decreasing fertility. But it is not enough. Fertility should be 2.1.
RAY SUAREZ: 2.1, that's replacement rate?
DR. SUGIRI SYARIEF: Yes.
RAY SUAREZ: Even after that success, the population isn't expected to level off until it reaches some 350 million.
And there's one other big question about how much of a role gandarusa will play in lowering that fertility rate: whether or not it gets the approval of Islamic religious leaders.
Some fundamentalist groups are opposed to any form of birth control. But Dr. Sugiri says most mainstream imams approve of family planning methods if they are not permanent and do not harm the body.
He is optimistic gandarusa will be available in Indonesian stores as early as next year. He's less confident the drug will be sold in the United States any time soon since strict food and drug regulations would require years of additional testing.