The female condom has never caught on in the United States. But in the third world, where it was introduced in the late 1990s, public health workers hoped it would overthrow the politics of the bedroom, empower women and stop the AIDS epidemic in its tracks.

It did not. Female condoms never really caught on there, either.

Only about 12 million female condoms are delivered each year in poor countries, compared with about 6 billion male condoms. Couples complained that the female version was awkward, unsightly, noisy and slippery — or, as Mitchell Warren, who was one of its earliest champions, now says, “the yuck factor was a problem.” Many women tried it, but in the end, it was adopted mainly by prostitutes.

Now scientists are trying again. A new design — much the same at one end, different at the other — has been developed, and its makers hope it will succeed where its predecessor failed.

“Over 15 years, there’s been no real competition, no second-generation product,” said Michael J. Free, head of technology at PATH, a nonprofit group based in Seattle that did the redesign. “There’s no lack of interest, but we’ve been stalled.”