Mark Zuckerberg, Chairman and CEO of Facebook, and his wife, Priscilla Chan, arrive for a State Dinner hosted by President Obama for Chinese President Xi Jinping at the White House in Washington, D.C, Sept. 25, 2015. (Molly Rley/AFP/Getty Images)

On Friday, with a picture on his Facebook page of a car seat, a stroller and his dog, Mark Zuckerberg announced he'd be taking two months of parental leave.

It wasn't a huge surprise: The first millennial CEO of a Fortune 500 company, Zuckerberg is part of a generation of men who place more value on work-life balance and taking time off with their children. His company offers four months of paid leave to both male and female employees. His chief operating officer is none other than "Lean In" maven Sheryl Sandberg, who not only advocates for more women in leadership but for more dads doing diaper duty. Had Zuck elected not to take substantial time off, it would have sent a mixed message.

Still, it was a huge milestone — both in the national discussion about parental leave and in the ongoing debate over the gender gap and how to solve it. To have a male Fortune 500 CEO say he will take two months of paternity leave and tout its benefits for children and families is the sort of leadership by example that's necessary, both to get more men to follow suit, and to help female executives feel they can do the same.

Of course, it's hard to know exactly what parental leave will look like for Zuckerberg. He and his wife certainly have the resources for any kind of professional assistance they could need during those first exhausting weeks. It seems unlikely he'll be completely out of touch from Facebook (though neither are many professional women who step away for a few months to take care of a new child). And while his post appears to say he'll take two months directly after his daughter is born, Facebook does allow employees to take their four months at any time during the child's first year.

But even if Zuckerberg is not taking the full four months' leave the company offers, two months is vastly longer than many professional men take off after the birth of a child. Research from Boston College's Center for Work & Family found in 2011 that 76 percent of fathers are back to work within a week of a child's birth or adoption; 96 percent return within two weeks. Last year, the same center found that less than 10 percent of fathers took six weeks or more off.

And that's among those who actually get it. Bureau of Labor Statistics data shows that only 13 percent of U.S. full-time employees had access to paid family leave in 2012 — much of which was likely maternity leave. According to the Society of Human Resources Management, just 17 percent of companies offered paid paternity leave in 2015.

That's starting to change, of course, as more companies — even those outside the cushy confines of Silicon Valley — add more paid leave for fathers or come up with innovative solutions. Goldman Sachs doubled its paid paternity leave to four weeks this summer, and Johnson & Johnson now gives new dads eight weeks of paid leave. In addition to adding six weeks of parental leave (it previously had no paid leave for new dads), Amazon recently began letting employees share part of their leave with a spouse who has none at their employers. (Amazon CEO Jeff Bezos owns The Washington Post.)

A few firms are also making time off after a baby more gender-neutral by giving both mothers and fathers the same amount of leave. Last week, the streaming music service Spotify said it would give both new mothers and fathers who work at the company six months of parental leave, joining companies such as Facebook and Netflix that have equal policies for men and women.

Such benefits serve two functions: They help attract employees, particularly younger ones, who are more interested in sharing parenting responsibilities and improving work-life balance. But they also make it possible for men to take the kind of leaves that could help improve the gender gap in both pay and leadership positions.

After all, if there's just as much of a risk that a male employee of parenting age could step out of a job for a few months as there is for a female one, it could help balance pay and promotions. Meanwhile, if fathers also have greater access to paid leave, it improves the chances more women will return to the workforce, or return sooner, potentially helping to ease the "motherhood penalty" that's seen as driving the gender gap in wages.

But all the extra weeks of paid leave in the world will do little if fathers, who still face a stigma when it comes to family leave in the workplace, don't see their colleagues or company leaders actually using it. Research has shown that men are more likely to take paternity leave if they see a co-worker taking it. As CEO of Facebook — and someone who has already been open about the miscarriages he and his wife have faced — Zuckerberg seems perfectly positioned to help.

So bring on the pictures of diaper duty, Zuck. These are Facebook baby pictures the world could stand to see.

Read also:

Advice on managing a new generation, from the head of HR at Facebook

How a business book from the ’80s became a cult classic in Silicon Valley

How do you erase the taboo of paternity leave?

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