When you're pregnant, going to the doctors can be exciting. You get to find out if you're having a boy or a girl. Maybe hear the baby's heart beat.

But in southern Africa, many women find out something else.

Sociologist Alison Groves recently ran a study in a town outside Durban, South Africa. They followed about 1,500 pregnant women. The results left her speechless.

"Thirty-eight percent of the women tested positive for HIV during pregnancy, which is just intense," Groves says. "And that is typical. It wasn't like we were only capturing very high risk women."

In fact, these women seemed like the least likely to get HIV. Most were married or in a committed relationship. Many said they were faithful.

How did so many of them get infected? Groves says they're not quite sure, but they have a clue: During the women's pregnancies — or right afterward, when their babies were tiny infants — 40 percent of them were abused. They were hit, beaten, threatened, emotional abused or even raped.

"These women are living in situations and circumstances that no matter where they turn, they're faced with the risk of violence — and then very negative health outcomes," Groves says. "And so much of that is beyond her own control."

That's exactly what's driving the AIDS epidemic in southern Africa: women's lack of control.

HIV is often considered a disease that affects gay men, drug users and prostitutes. That's true in many places. But in southern Africa the epidemic has taken a surprising turn. Young women — at many economic and educational levels — are bearing the brunt of the epidemic.

AIDS is the biggest killer of young women in southern Africa. Every day more than a thousand are infected.

In many places, women have no way to avoid exposure to HIV.

"Women do not have control over their lives sexually," says Zeda Rosenberg , the founder and CEO of the nonprofit International Partnership for Microbicides.

Women may not know their partners' status and may be afraid to ask them to get tested. And they often do not control when they have sex.

"Rape, both within and outside a relationship is very common," Rosenberg says. A report from the World Health Organization found rates of sexual abuse by a partner were as high 60 percent in some parts of African. And in South Africa, more than a quarter of men said they've raped at least one women.

And condoms are often out of the question. "Men either threaten violence if they are asked to use a condom or actually incur violence," she says. "It is pervasive that the power dynamics here favor men."

But Rosenberg is trying to tip that balance. And she's doing it with an unlikely tool: a vaginal ring .

It's soft and flexible, about the diameter of a lime. The ring sits inside the vagina and releases anti-HIV drugs into the reproductive tract.

Most important, Rosenberg says, it's secretive.

"No one knows you have it. And it doesn't interfere with the sexual experience," Rosenberg says. "It can help a woman control her body and her health without necessarily challenging the man."

Rosenberg has been working on the ring for more than a decade. She finally has evidence that it works.

At the International AIDS Conference this week in Durban, she and her colleagues announced results from a big clinical study of 2,600 women. The ring was up to 70 percent effective at stopping HIV when women wore it regularly.

Rosenberg is now trying to get the World Health Organization to approve the ring. She hopes to have it available for all women by 2018.

Many activists and researchers at the conference were cautiously optimistic.

"We can all be very excited about the ring," says Dazon Dixon Diallo , the president of the nonprofit Sister Love — which helps women fight HIV.

The ring provides the second tool women have now for preventing HIV that they control — and they can keep secret from men. The first is taking a daily anti-AIDS pill, which is known to reduce infections by more than 90 percent.

There's also the female condom. But it's difficult to use and is clearly perceivable by men during sex.

But none of these methods is perfect, Diallo says. "Getting people to use these products is the challenge."

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