It was a trickle at first. But then came the flood of viral menstruation moments. In just this past week—as Indiana women called the governor about their periods in protest of an abortion bill—TechCrunch propelled Flex, which makes menstrual cups optimized (and marketed) for period sex, around the internet by singling it out at Y Combinator’s Demo Day. And the New York Times profiled at length the tampon blood testing company NextGen Jane.

“I don’t know if ‘wet tampon’ had ever appeared in a New York Times article,” says Ridhi Tariyal, a cofounder of NextGen Jane. (It hadn’t. And for the record, the phrase had never appeared in WIRED either.)

Trading period woes has long been part of female bonding, but period talk now seems to take on a dimension of social awareness. Talking about periods is ?. When the MTA waffled on running ads for the Thinx’s period panties, which can be worn without a pad, CEO Miki Agrawal dashed off emails to a couple reporters with the subject, “Scandal with the MTA and use of the word period.” They bit, and Thinx’s ads went viral online. Why did it turn into such a big deal? “It was the patriarchal double standard—in New York City, the most progressive city in the world,” says Agrawal, tossing out all the right buzzwords.

The investment world, on the other hand, kind of is the patriarchy, and I imagine has negligible up-close-and-personal menstrual experience. (Only 4.2 percent of senior partners at venture capital firms are women, according to a Fortune analysis.) Agrawal describes making one male friend wear a pad. “I said, ‘Sit down and stand up and then tell me how you feel. He was just like, ‘This is ridiculous,’” she recalls. He ended up investing in Thinx.

So to pitch a business aimed at women to male investors, founders have also staked out canny positions. Glow, which makes a suite of period tracking and baby apps, bills itself as a quantified self company first. And Flex, says founder Lauren Schulte, was conceived as a soft disposable menstrual cup—it looks a bit like a squat condom. Use during sex was purely incidental. But the period sex angle is what really drew women in. It’s also one of the few period problems a man might have intimate knowledge of.

No More Pink

How these startups appeal to women is fascinating, too. Gone are the flowers and pastel palette that have dominated the feminine hygiene industry since Kimberly-Clark convinced the Ladies’ Home Journal to run its “tasteful” ads. Flex actually quite resembles the Instead Softcup, a disposable menstrual cup that’s been around since the 1990s. But where Instead is pink, Flex is black and gold. Its sleek box looks like it could hold expensive hand cream.

Rejecting the soft femininity and euphemistic blue liquid of old tampon ads is one way these companies are pitching themselves to young women. “We are so much more than pink and flowers and these horrible stereotypes. We’re savvy. We’re empowered,” says Jennifer Tye, head of marketing and partnerships for Glow. But these sleek designs can’t erase the stigma around periods on their own. When Tariyal went around fundraising for NextGen Jane, she noticed her pitch left even female potential investors viscerally icked out.

Flex

Flex promises blood-free period sex. Thinx, which look like regular (and even sexy) panties, make it easier to hide your period. But therein lies the contradiction in selling these products using period empowerment. If periods are so great, why hide them? Sharra Vostral, author of Under Wraps: A History of Menstrual Hygiene Technology, points out that the invention of tampons allowed menstruating women to “pass” as non-menstruating women, whether that’s to go to the pool or wear leggings or anything else that might otherwise broadcast your menstrual cycle. “If you don’t do it, you get stares or you feel shame or someone takes you aside,” Vostral says. The passing is necessary because the stigma exists.

In an email, Schulte writes her intentions with Flex were pragmatic. “Just because I personally don’t find period blood ‘icky’ doesn’t necessarily mean that I want it all over some Egyptian cotton sheets, you know what I’m saying?” But still. It’s hard to argue that Thinx or Flex don’t also appeal to the conventional idea that menstrual fluid should be kept out of sight. As one woman says in a testimonial on Flex’s website, “I hate feeling self-conscious about having sex when I'm on my period.” The most radical moment in recent period virality was when a woman ran the London Marathon while free bleeding—though that still feels like the exception rather than the norm.

NextGen Jane might also be onto to something here. Those new tampon alternatives are better ways of collecting your “trash,” says Tariyal. “We’re trying to push the message a little more aggressively: It’s not trash. It’s something useful.” Along with her cofounder Stephen Gire, she is developing a test for endometriosis by sequencing the genes expressed in cells shed in period blood. Even the scientific community has barely considered the fact that period blood could be teeming with medically useful information. (The scientific community being nearly as patriarchal as the investment community, presumably.) Since the Times story, the NextGen Jane team has heard from lots of women jazzed about the idea their period blood could be diagnostic gold—the period movement might be slowly trickling into medicine, too.