Women-only co-working spaces are the newest rage in the #MeToo age

Just say no — to bro culture. That's the rallying cry behind an emerging type of co-working space, created by women and for women, and expanding to industrial-chic streets across the country.

From cozy community start-ups like The Coven in Minneapolis, to a business with much larger ambitions, like The Wing — which has locations spreading internationally — the women-only office share is the "it" work sanctuary for the #MeToo era.

The Wing gets most of the attention, and not just because the design color scheme skews millennial pink. In just over a year and a half, the start-up has raised more than $40 million from investors, including from WeWork, the co-working giant valued at $20 billion. The Wing now has three spaces in New York City with a total of 22,500 square feet, another in Washington, D.C., and three more coming before the end of this year to Brooklyn, Los Angeles and San Francisco. Seattle, Toronto and London are on track for 2019.

"We're still a tadpole, but we're swimming fast," said co-founder Audrey Gelman, 30.

The basic concept is to create a safe and supportive work environment — a professional home base — where women can take risks in the company of female collaborators and mentors without the sweat or frustration of laboring in a man's world. By day, work gets done; at night a bar opens and speakers give talks. There are beauty stations, hair-braiding workshops and lactation rooms. Membership begins at $215 a month.

Gelman, a glamorous former political publicist who helped inspire the Marnie character from the HBO Show "Girls" (she's one of "Girls" creator Lena Dunham's best friends) speaks of creating "a global sisterhood" that resurrects the concept of the Women's Club movement of the 19th and early 20th century, when 5,000 women's groups nationwide "gave women space to be themselves and express themselves."

The co-working idea occurred to Gelman while on a commute from New York to Washington for her PR job. She wanted a place to unwind and maybe even shower between meetings, but couldn't find one. With co-founder Lauren Kassan, a veteran of fitness start-up ClassPass, The Wing took flight quickly. It was helped along by an investment from SoulCycle founders Julie Rice and Elizabeth Cutler, and Susan Lyne of BBG Ventures, who once oversaw Martha Stewart Living Omnimedia.

The founders collaborated with an all-female design and architecture team and launched in October 2016, on the eve of the presidential election. "We were expecting a very different political outcome," Gelman said, recalling the 300 Wing members who gathered to watch the results come in that night. "But our mission remained the same: the advancement of women through community."

A sense of community is what's driving most of these ventures.

In Twin Cities, Minnesota, The Coven opened this past spring as "a modern, diverse social club," as it calls itself, and coworking space for women. Co-founder Alex West Steinman says the company raised $315,000 through crowdfunding efforts and opened with over 200 founding members. "We've got women, non-binary folks, different ages, races and genders — it's a space that's truly intersectional," she said. "It's so affirming to see people collaborating who otherwise wouldn't have met. Here, they get support, give advice and share work on projects."

Hera Hub was a pioneer in the niche, having launched in San Diego in 2011. Founder Felena Hanson is quick to note that female co-working is not about isolating women from men. "We're female-focused not to be exclusionary but because women helping women makes good business sense," said Hanson. "Women have long operated in a business world we didn't create. So many women feel like outsiders in various industries that it's great to create room where our needs come first."

The bro culture that's come to define Silicon Valley can make business difficult for women, Hanson said. But at a place like Hera Hub, corporate competitiveness tends to take a back seat to compassion and vulnerability. "I think women find it easier than men to admit we don't have all the answers. People here aren't puffing themselves up and acting like they know everything they're talking about. If someone has a pitch next week and they're not a thousand percent confident, it's okay to say, I don't know what I'm doing."

Gretchen Spreitzer, who studies coworking as faculty director for the Center for Positive Organizations at the University of Michigan, says the rise of corporate coworking behemoths like WeWork shows how big these businesses can grow. The challenge is providing specialized services that continue to attract members. "These companies aren't cheap to run," she said.

In April, WeWork completed a $700 million bond deal. The bond deal paperwork revealed that the company lost nearly $1 billion last year, and its expenses more than doubled, while WeWork has $18 billion in lease payments to make.

"Real estate in prime locations is expensive and if spaces don't have that sense of community and culture where people want to pay a fee, it's hard to sustain over time," Spreitzer said.

"The Wing will continue to open in new cities based on demand from both new and existing members, based on where they live and travel to frequently," Gelman said.

Cash flow isn't the only issue. In March, The Wing was put under investigation by New York City's Commission on Human Rights because of its women-only policy and what some perceive as discrimination. That set off a tweet storm of support, with celebrities like Monica Lewinksy posting #IStandWithTheWing.

"Because of the history of women in this country — and even more so in this time we live in — it is important to protect and foster the work of The Wing and similar space that give women a positive and safe space to thrive," Gelman said in response to the investigation.

She's keeping an eye on the future while also thinking about the past. "It's so powerful when women in their 60s or older come in and tell us how happy they are to have a place like this," she said. "Women weren't allowed to apply for credit cards until the 1970s. Now these older women come in and say, 'I want my granddaughter to be a Wing woman.'"

—By David Hochman, special to CNBC.com