Paid parental leave is a luxury in the United States. We’re one of three advanced and not-so-advanced countries in the world without it.  Only 11 percent of all workers get it. And few of them are fathers. Dads, if they’re lucky, may get one day to a week, or two at most, one recent study found. That sets up the dynamic that Mom becomes the primary caregiver, not just at the start, but, like, forever. American moms, on average, do double the housework and child care of their spouses, even when they work full-time.

So what happens when you give dads more time? Take a look at what happened in Iceland.

In 2000, Iceland, pushed mainly by dads who wanted more time with their babies, sought to break the pattern that leads to traditional gender roles. Lawmakers changed their paid parental-leave policy and began requiring dads to take a portion, or the whole family would lose the time — a so-called “use it or lose it” policy that other Nordic countries had already adopted in the 1990s. Before that, families in Iceland were supposed to “share” a six-month paid leave. But most often, mothers took all of it. And, three years later, had most of the caregiving responsibilities.

The point of the change, according to the legislation, was “to ensure that children enjoy the care of both parents. The second aim of the law is to enable both women and men to coordinate family life and work outside the home.”

And that’s exactly what happened, according to a new study of more than 5,000 parents in Iceland. (You can get a pdf of the study by clicking here.)

Now, about 90 percent of all fathers in Iceland take paid parental leave, significantly more than before the “Daddy days” policy. Before the policy, about 34 percent of  all parents shared care equally when their first born child turned 3. After the policy, nearly 60 percent did. The charts here show data on cohabiting parents only, and the percentage sharing care was even higher, at 70 percent.

The fiscal crisis of 2008 that bankrupted the country has led to cuts in paid parental leave. Politicians say they are committed to the program and have vowed to restore funding and extend the leave. Now, moms get three months, dads get three months and the family has three months paid leave to share. In a few years, politicians promise, they’ll move to what they call a 5-5-2 system, five months each of “use it or lose it” leave for moms and dads and two to share. Still, researchers noted in the study that the number of days of paid leave fathers take has fallen from a high average of 101 days in 2007 to 84 days in 2011, while mothers held fairly steady at about 180 days.

It remains to be seen if that will mean more diaper duty for moms down the road.