Mark Zuckerberg, the CEO of Facebook, announced last week (on Facebook, of course) that he is planning to take two months of paternity leave when his daughter is born. In his post, Zuckerberg noted that studies have found better outcomes when parents take time off from work to be with their newborns. He also pointed out that his company offers U.S. employees four months of paid maternity or paternity leave.

Zuckerberg is right: There are many research-backed reasons for parents to take leave. Still, while paternity leave has been expanding at American companies, such as Netflix and Microsoft, it is far from being a mainstream benefit.

Zuckerberg and his wife, Priscilla Chan, live in Palo Alto’s Crescent Park neighborhood. California, along with Rhode Island and New Jersey, are the only three states in the U.S. that offer paid family leave to workers of any gender. The existence of such laws is evidence of a drift toward gender equality at work and at home, but the problem is that even men who are offered paid leave often don’t take it, for fear of social and professional repercussions in the office hierarchy.

So how do these laws impact new dads? Using data from the Census and the American Community Survey, a group of researchers found that the California Paid Family Leave program, which was started in 2004 and pays new mothers and fathers about 55 percent of their salaries during time off (up to $1,104), has increased rates of leave-taking for both moms and dads. (The program covers any worker in California who pays payrolls tax.) The results, reported in a new National Bureau of Economic Research paper, show that fathers in California are 46 percent more likely to take time off in the first year of their child’s life when they have the option of paid leave, compared to when they don’t.

“These results, when combined with the relative lack of employer-provided paternity leave in the United States, suggest that many new fathers respond to expanded opportunities to take paid family leave," wrote the researchers. They speculated that as these programs start getting adopted in other states, new fathers will start taking more time off.

There are a few interesting patterns that the researchers noticed in which types of dads tended to take paternity leave. They found that fathers were much more likely to take time off for first-borns than they were for subsequent births. Secondly, this effect was much larger for fathers of sons rather than daughters—a trend they blamed on “men’s long-run attitudes about gender equality.” They also found that men in female-dominated professions were much more likely to take paid leave.

By those trends, Zuckerberg, as the first-time father of a baby girl working in the tech industry, is actually a bit less likely than other dads to take leave. But he happens to work at one of the few companies that takes exceedingly good care of its new parents, and perhaps just the fact that Zuckerberg is taking his leave so publicly will make a difference for other fathers-to-be: In Norway, men were 11 percent more likely to take paternity leave if their colleagues did so. The researchers of that study noted that the effect snowballs as more and more men take time off.