Humans, like other animals, live to reproduce. And when they can't, they're willing to pay a lot for a helping hand. In America, some use credit cards, 401(k)s, and even loans to pay for in vitro fertilization that can cost as much as $12,000 for each round.

The newest way to fund the family unit is to ask strangers. Crowdfunding has become a popular mechanism for many couples who can't afford the high costs of IVF, or adoption and surrogacy.

"It's not an easy thing to share publicly," says Crystal Barrett, 33, who used youcaring.com to raise money for medications and other costs while undergoing several cycles of IVF treatment. "But my husband and I were kind of between a rock and a hard place." Within 45 days of posting their cash goal in December, she and husband Josh reached their target of $1,500. She is now six months pregnant.

The Barretts' campaign was modest compared with the actual cost of IVF, which can rise to more than $20,000. Crystal kept their needs front and center with potential online donors by using social media and blogging regularly about her test results, ultrasounds, and what she'd heard about certain medications. "It was," she said, "a job in itself."

Funding for IVF has become a robust category at GoFundMe.com, where more than $3.6 million has been raised across more than 1,700 IVF campaigns, with almost 37,000 individual donations. Total IVF gifts and campaigns have increased every year since the company's launch in 2010. On Giveforward.com, the site Barrett used, the category that includes both IVF and adoptions is the fastest growing, up 429 percent over the first eight months of this year compared with the same period in 2015, according to Josh Chapman, the company's chief executive officer. (He said the increase is evenly split between IVF and adoptions). He notes, however, that such efforts tend to raise only 20 percent of what more traditional medical assistance campaigns bring in.

A big driver of child-related campaigns is a lack of insurance. Insurance coverage for IVF is available at only 26 percent of companies, according to a 2016 Society of Human Resource Management Employee Benefits survey, and those who do cover the treatments may cap the lifetime maximum benefit as low as $5,000.

For those who aren't comfortable with traditional crowdfunding sites, there's a crowdfunding option on a sophisticated fertility app from Glow Inc., a company headed by PayPal co-founder Max Levchin and Mike Huang, a former director of product management at Google.

The informational and tracking app lets women input all sorts of data to monitor their reproductive health and alerts them and their partner to the best time to conceive. Glow also has a nonprofit Glow First program, which it calls crowdfunding for babies. Users of the app can choose to give $50 a month to a shared pool of money for 10 months while trying to get pregnant naturally (the site states 10 months is how long it takes most women to get pregnant). After those 10 months, money in the fund is split evenly among the women in the group who hadn't yet conceived, sending a check directly to an accredited fertility clinic of the user's choice. The program's first such group, numbering fewer than 50 women, had an $1,800 payout per eligible person-three times their contribution.A third Glow endeavor, Glow for Enterprise, aims to be a wellness benefit for workplace health plans. So far, it's found mainly in technology companies and is available to employees of Lyft, Pivotal, Zefr, EventBrite, Evernote, and Domo, according to Glow. The idea is for the employer to pay the $50 per employee, per month, for however many of their employees enroll in the program. Employers wouldn't know the names of those who enroll; users would prove their proof of employment to Glow First by entering their work e-mail or scanning a pay stub.

Barbara Collura, CEO of Resolve: The National Infertility Organization, says she's noticed a lot of prospective parents turning to crowdfunding but was more shocked to see another trend. The group did a survey asking women who had done an IVF cycle in the past three years how they paid for out-of-pocket costs.

"Most people used a credit card, about 26 percent used a loan from the bank, and 20 percent cited donations from friends and families-that would be your crowdfunding," said Collura. Ten percent chose the "other" category, and many people wrote in that they'd raided their 401(k) retirement savings.

As it turns out, early on in her IVF treatments, Crystal Barrett did that, too. "I didn't want to," she said. "But I was paying off the credit card and personal loans I'd also taken out for IVF."