Yahoo named Marissa Mayer, a key Google team member, to be its next CEO. Mayer confirmed shortly afterwards that she is also pregnant. (OLIVER LANG/AFP/GETTY IMAGES)

Yahoo stunned the world Monday when it named Google executive Marissa Mayer as its fifth CEO in four years. And then Mayer did it again by announcing she is six months pregnant.

That there are now a handful of major technology companies led by women (Virginia Rometty at IBM, Meg Whitman at Hewlett-Packard, and now Mayer at Yahoo) already marks a big milestone. That Mayer is just 37 years old is a rarity in jobs like this, too. But this is also almost certainly the first time a pregnant woman has ever been named CEO of a Fortune 500 company.

What’s most remarkable about the news, first reported by Fortune, is not just that Mayer would decide to take on a job of this difficulty when she is about to go through such changes in her personal life. Every such decision is a personal one, no matter the scale or how “superhuman, rich & in charge,” as Anne-Marie Slaughter tweeted, Mayer may be. (Mayer told Fortune that she expects her maternity leave to be “a few weeks long” and that she’ll “work throughout it.”)

No, what’s most remarkable is that the board, according to Mayer, did not reveal any concerns about hiring a CEO who is expecting a baby in three months. “They showed their evolved thinking,” she told Fortune. Their decision is worth applauding in any industry, but particularly in Silicon Valley, which is known for being extremely male dominated and having few women on boards, and where it makes news that top senior women leave work at 5:30 p.m.

It may also say something about how much Yahoo needed Mayer. The company, as PandoDaily’s Sarah Lacy pointed out, has tried on all manner of leaders in recent years: the studio mogul, the returning entrepreneur, the hard-charging, operations-minded veteran. But with Mayer, it gets “a CEO with bona-fide Web tech chops,” a Google veteran and a self-described “geek”—all things that a company like Yahoo sorely needs, given the kind of strategic and innovation challenges it faces.

If Yahoo continues to struggle, I'm already dreading the unfortunate questions some people will inevitably ask about whether Mayer is, ahem, “distracted.” Unless she pulls off a nearly instant turnaround, it’s hard not to worry her leadership will be second-guessed more than most.

But for now, I’ll celebrate the fact that Mayer’s appointment fundamentally shifts the discussion on women in leadership. Every board or leader that has ever questioned promoting a woman—whether she’s pregnant, has small children, is in her 20s, or in her 60s—now has a new standard by which to judge their decision. If Yahoo’s board can put a pregnant woman in her 30s into one of the most challenging, high-profile jobs in technology, maybe every other board out there can judge women simply on their merits, too.

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