"Probably the biggest burden is child care," Bovino told CNBC. While she credits men today with helping more, "women (still) do the lion's share of child care and elder care as well." Maternity and family leave also impacts the decision for women to rejoin the workforce, she added. Bovino said the S&P study found that 39 percent of mothers took "a lot of time out of the workforce when they have children, and 25% don't come back." Her research found 24 percent of fathers take significant time off for child or family care.

What prevents women from entering STEM fields and what drives them out? Research points to unconducive work environments and a lack of workplace policies that support a healthy work-life balance. Access to affordable, quality childcare is one such policy area that can significantly effect working parents’ career choices and earning potential. Examining workplace policies, IFC, a member of the World Bank Group, found in its latest report that companies that support employees’ childcare needs can strengthen their bottom line by recruiting and retaining talent, reducing absenteeism and turnover, and increasing employee satisfaction and productivity.

"Gender really shouldn't matter. It is similar to the way in which nursing used to be a female profession and as society's attitudes changed more and more men have become nurses."