The United States is the only developed nation on Earth that does not provide paid family leave across the board despite widespread support among the public for some form of guaranteed leave. According to a Pew Research Center survey, most Americans believe employers would even find some benefit in offering paid leave. So why is it so controversial?

Ford Professor of Economics at MIT Jon Gruber joined Boston Public Radio on Wednesday to break down the pros and cons of the policy.

He said the U.S. lags behind other nations, even for job protections with family leave.

"Guaranteed job protected leave didn't even exist before Bill Clinton put in the Family Medical Leave Act," Gruber said. "Now, you get 12 weeks of guaranteed unpaid leave. Your job has to be held protected for 12 weeks. That is by far the lowest of anywhere in the world."

Gruber said there is evidence, thanks to studies around the world, that paid maternity leave is good for the mother and child, and does not result in significant cost to employers.

"The firms managed to cover it pretty well, they hired some temp workers, existing workers worked a little harder, though they didn't seem much unhappier, for example they didn't take more sick leave or anything, and it looked like the firm didn't really suffer," Gruber said, referring to a study done in workplaces in Denmark. "The evidence now is pretty clear that this is something which is going to be very beneficial for women's attachment to the labor force, probably beneficial for their kids, and won't be that costly in terms of economic efficiency."