Companies that want women to advance in the workplace and receive equal pay to men are faced with an interesting paradox: Generous paid maternity leave policies, usually meant to support work-life balance for women, may serve to prop open the gender wage gap, and contribute to the disturbing dearth of female top executives. Paternity leave, it turns out, may actually have a stronger impact on gender equity in the workplace.

As we know from Sheryl Sandberg and President Obama, the U.S. still has a long way to go to achieve gender equality in offices. After closing for decades, in 2002 the gender pay gap in the U.S. stalled at around 77 cents to the dollar, and remained there through 2012. In addition, only 23 women currently hold the top position at Fortune 500 companies, reported Bloomberg in December.

Though the reasons for these gaps are varied and complex, most experts agree that career interruptions — i.e. taking time off to have children — are a key factor. After child birth, women are more likely than men to take long leaves, scale back to part time work, or leave the workforce entirely, instead taking on more responsibility at home. Generous maternity leave policies naturally reinforce this tendency.

In a recent article in The Atlantic, Liza Mundy explained why paternity leave could be the key to a more equal workplace.

The genius of paternity leave is that it shapes domestic and parenting habits as they are forming... Paternity leave is a chance to intervene at what one study called 'a crucial time of renegotiation': Those early, sleep-deprived weeks of diaper changes and midnight feedings, during which couples fall into patterns that turn out to be surprisingly permanent. [The Atlantic]

The idea is that if men start taking on more responsibilities at home, women are able to return to work more quickly — a plus for everyone, even non-parents.

So, to advance gender equality, should companies simply offer generous and equal parental leave to moms and dads? Apparently, that would be way too easy. Even when paid paternity leave is available, according to a 2011 survey of four Fortune 500 companies, men often opt to stay at work anyway. Of the 85 percent of new fathers who take time off after the birth of a child, the vast majority only take a week or two, said the study. The result of men's tendency to choose work over leave is that some of the countries with liberal parental leave policies actually have higher pay gaps among men and women, says a Pew report.

So why are men so reluctant to take advantage of their benefits? Babble's Brian Gresko suggests it has to do with the "power of outdated cultural assumptions that the workplace is where the man belongs." He goes on:

Even if the father doesn't feel this way himself, his boss or colleagues might. As one friend put it, her husband wasn't so much scared of the baby as he was scared, "he would be perceived as 'less committed' in his career" for taking time off from his job. [Babble]

A recent study from the University of Toronto's Rotman School of Management backs up Gresko's theory. In a survey of 232 middle class union members, researchers Jennifer Berdahl and Sue Moon found that "devoted fathers who spend a lot of time caregiving feel ridiculed by co-workers for not being man enough," says AOL News.

They found that men who spent a lot of time with their children were harassed the most — by far. Men with no children were also harassed a lot, while men who had children but let their wives do most of the caregiving were largely immune from the bullying. After all, they were playing the part of the traditional breadwinning dad.

Women also faced a similar kind of harassment around the issue of caring for children, but the pattern was reversed: Women without children got the worst of it, while mothers who spent a lot of time with their kids experienced the least. [AOL News]

Men, it turns out, can be coerced into taking time off to spend with their kids, despite social pressures. Norway, Iceland, Germany, Finland, and other countries have experimented with policies that offer men financial incentive to take leave, "which helped men feel they were financially supporting their families even when they were at home," said Mundy. But the U.S., which according to a recent Pew report has the least liberal paid parental leave policies of 38 developed nations, is unlikely to pass these types of policies anytime soon. For now, it's up to the fathers to brave social pressure and take the leave when the company allows it.