Care-giving responsibilities often fall disproportionately to women, which keeps them from moving up the ranks in their career and allows the pay gap to persist, Zalis said.
Women in middle management positions are more likely than men to leave the workforce to raise their children and care for family members, which means fewer women will fill leadership roles. While women and men start out in equal numbers in the workforce, only 6.4 percent of CEOs at fortune 500 companies are women.
Research suggests that when companies offer optional paternity leave, men will likely opt out for fear of career repercussions. One survey shows that while 66 percent of women take all their paid maternity leave, only 36 percent of men use their paternity leave.
Zalis suggested that companies should have mandatory paid leave policies for both men and women, to eliminate the stigma fathers may associate with taking time off.
"We need to work on re-writing the rules. There's a mother penalty," Zalis said, "but by creating a mandatory parental leave for both men and women, where parents take the same amount of time off — that would take that bias off the table."
When men take leave, women are able to return to work sooner and move more quickly into higher paying leadership roles, Zalis said. Research also shows that when women take longer maternity leaves, the rate of returning to work drops nearly 50 percent.
Zalis said that company leaders should make sure that the firm's parental leave policy is inclusive for everyone in the workforce. She cited Unilever, which was named one of the "Best Companies for Dads" by Working Mother magazine for offering "generous and inclusive" paid parental leave for men and women.
"At Unilever, if men don't take [paternity leave], the CEO calls them and asks why they didn't take it," she said. "What he's saying is that he wants nurturing, empathetic care-giving leaders, and doesn't not want people to take time with their families."
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