So while the companies' inclusion of egg-freezing as a health benefit may certainly be part of the Valley's notorious perks arms race, you could also read it as a sign that egg-freezing has reached a kind of cultural normalcy. In 2008, the American Society of Reproductive Medicine called the technique "experimental," warning, based on current evidence, that it "should only be offered in that context." In 2012, however, citing sufficient evidence to "demonstrate acceptable success rates in young highly selected populations," it lifted that designation.

Since then, according to NBC's Danielle Friedman, doctors have seen a steady increase in the number of women who have sought out the procedure. In New York and San Francisco, she notes, fertility doctors report a near doubling in requests for it over the past year alone. And advocates and facilitators of egg-freezing—firms and forums with names like Eggsurance, Extend Fertility, and, yep, EggBannxx—claim that Facebook and Apple aren't alone in their egg-freezing offerings: Large law, consulting, and finance firms, they say, are also starting to cover the costs of the procedure for their employees. (If so, though, those companies aren't being public about it.)

The technology that allows for egg-freezing was developed in the late 1980s to protect the fertility of women with cancer—a means of preserving eggs that would otherwise likely be destroyed by chemotherapy treatments. As its success rates have improved, however, otherwise healthy women, especially those in their 30s and 40s, have turned to it as a more time-oriented insurance policy—a way to extend, possibly, their reproductive years. The development of vitrification, an improved technique for flash-freezing the eggs, has added to the procedure's popularity. In a 2009 survey, some two-thirds of U.S. fertility clinics claimed to offer egg-freezing as an elective procedure.

Is the procedure effective? It's hard to tell. A 2013 article in the journal Fertility and Sterility shared the results of a meta-analysis of more than 2,200 cycles of freezing and thawing, analyzed according to the age at which women froze their eggs. The probability of a live birth after three cycles—rather than the two that a $20,000 benefit would pay for—was 31.5 percent for women who froze their eggs at age 25, 25.9 percent at age 30, 19.3 percent at age 35, and 14.8 percent at age 40. The ASRM warns against relying on egg-freezing as a way to extend fertility.

So egg-freezing is, at this point, more about assurance than insurance. It is marketed largely under the auspices of "peace of mind," a way of reassuring women that, regardless of their age, they still have time to conceive. And now, that marketing is shifting to the bureaucratic terrain of the benefits package. "Maybe you haven’t found Mr. Right just yet or perhaps you would like more time to focus on your education or career," EggBanxx's website puts it. "Whatever the reasons, freezing your eggs now will allow you to tackle conception later." As the "Let's Chill" attendee Donna Kanze, 35, told the New York Post: “I want to take my fertility into my own hands, rather than put pressure on the person I have my next relationship with."

We want to hear what you think about this article. Submit a letter to the editor or write to letters@theatlantic.com.