Two Silicon Valley giants now offer women a game-changing perk: Apple and Facebook will pay for employees to freeze their eggs.

Facebook recently began covering egg freezing, and Apple will start in January, spokespeople for the companies told NBC News. The firms appear to be the first major employers to offer this coverage for non-medical reasons.

“Having a high-powered career and children is still a very hard thing to do,” said Brigitte Adams, an egg-freezing advocate and founder of the patient forum Eggsurance.com. By offering this benefit, companies are investing in women, she said, and supporting them in carving out the lives they want.

When successful, egg freezing allows women to put their fertility on ice, so to speak, until they’re ready to become parents. But the procedure comes at a steep price: Costs typically add up to at least $10,000 for every round, plus $500 or more annually for storage.

With notoriously male-dominated Silicon Valley firms competing to attract top female talent, the coverage may give Apple and Facebook a leg up among the many women who devote key childbearing years to building careers. Covering egg freezing can be viewed as a type of “payback” for women’s commitment, said Philip Chenette, a fertility specialist in San Francisco.

The companies offer egg-freezing coverage under slightly different terms: Apple covers costs under its fertility benefit, and Facebook under its surrogacy benefit, both up to $20,000. Women at Facebook began taking advantage of the coverage this year.

Why freeze?

While techniques and success rates are improving, there's no guarantee the procedure will lead to a baby down the road. The American Society for Reproductive Medicine doesn’t keep comprehensive stats on babies born from frozen eggs – in fact, the group cautions against relying on egg freezing to extend fertility – though experts say the earlier a woman freezes her eggs, the greater her chances of success. Doctors often recommend women freeze at least 20 eggs, which can require two costly rounds.

But in the two years since the ASRM lifted the “experimental” label from egg freezing, experts say they’ve seen a surge in women seeking out the procedure. Fertility doctors in New York and San Francisco report that egg-freezing cases have nearly doubled over the past year.

For many women, taking the step to boost their chances of having kids in the future is worth the uncertainty. A majority of patients who froze their eggs reported feeling “empowered” in a 2013 survey published in the journal Fertility and Sterility. Women who know they want kids someday “can go on with their lives and know that they've done everything that they can,” said Chenette.

Egg freezing has even been described as a key to “leveling the playing field” between men and women: Without the crushing pressure of a ticking biological clock, women have more freedom in making life choices, say advocates. A Bloomberg Businessweek magazine cover story earlier this year asked: Will freezing your eggs free your career? “Not since the birth control pill has a medical technology had such potential to change family and career planning,” wrote author Emma Rosenblum.

New ground

Silicon Valley firms are hardly alone in offering generous benefits to attract and keep talent, but they appear to be leading the way with egg freezing. Advocates say they’ve heard murmurs of large law, consulting, and finance firms helping to cover the costs, but no companies are broadcasting this support. “It’s very forward-looking,” said Eggsurance’s Adams.

Companies may be concerned about the public relations implications of the benefit – in the most cynical light, egg-freezing coverage could be viewed as a ploy to entice women to sell their souls to their employer, sacrificing childbearing years for the promise of promotion.

“Would potential female associates welcome this option knowing that they can work hard early on and still reproduce, if they so desire, later on?” asked Glenn Cohen, co-director of Harvard Law School’s Petrie-Flom Center for Health Law Policy, Biotechnology, and Bioethics, in a blog post last year. “Or would they take this as a signal that the firm thinks that working there as an associate and pregnancy are incompatible?”

But the more likely explanation for lack of coverage is simply that egg freezing is still new, and conversation around the procedure has only recently gone mainstream. “I think we've reached a tipping point,” said Adams. “When I used to say ‘egg freezing,’ people would stare at me with their mouths open.” Now? Most people know someone who’s done or considered it.

Many large companies adopt new benefits in response to employee demand – firms have recently started to offer benefits for transgender employees, for example. As women’s awareness of egg freezing grows, more employers may jump on the band wagon.

“The attitude toward egg freezing is very different,” and more positive, than just a few years ago, said Christy Jones, founder of Extend Fertility, a company that offers and promotes egg freezing across the country. Women are making the proactive decision to freeze their eggs at a younger age, and the choice is "more one of empowerment than 'this is my last chance.'"

EggBanxx, the first service to help women finance egg freezing, has recently begun to capitalize on this shift by hosting “egg-freezing parties,” where experts educate guests. “Maybe you haven’t found Mr. Right just yet or perhaps you would like more time to focus on your education or career,” the company website says. “Whatever the reasons, freezing your eggs now will allow you to tackle conception later.”

‘Back to work the next day’

Women generally need about two weeks of flexibility for one cycle of egg freezing. After about ten days of fertility drug injections, patients undergo a relatively short outpatient procedure – and they’re “back to work the next day,” said Lynn Westphal, Associate Professor Obstetrics and Gynecology at Stanford University Medical Center. From there, eggs are frozen and stored until a woman is ready to use them, at which point she’ll begin the process of in vitro fertilization.

Once a woman freezes her eggs, she may never return to use them, fertility doctors report. Some women get pregnant the old-fashioned way, others make different life plans. Westphal compares egg freezing to car insurance: You hope you don’t have to use what you’ve put away, but if you find yourself in a situation where you need to, you’re glad to have the protection.

Will the perk pay off for companies? The benefit will likely encourage women to stay with their employer longer, cutting down on recruiting and hiring costs. And practically speaking, when women freeze their eggs early, firms may save on pregnancy costs in the long run, said Westphal. A woman could avoid paying to use a donor egg down the road, for example, or undergoing more intensive fertility treatments when she’s ready to have a baby.

But the emotional and cultural payoff may be more valuable, said Jones: Offering this benefit “can help women be more productive human beings.”