We all know that the addition of little ones to your family will mean that you'll be spending more money. But does it also mean you'll be bringing home less?

According to the latest research, that might depend on your gender. A Bureau of Labor Statistics report found that while working women with children younger than 18 tend to earn less than those without minor children, the opposite is actually true for dads: Men with young kids bring home bigger paychecks than those who don't have children under 18.

The data show that in 2012, working mothers with young kids had median earnings of $680 per week — while those without young children raked in about $697. Meanwhile, men earn a so-called "bonus" for having young children: Those with minors reel in median weekly earnings of $946, compared to just $799 for those without.

"I think parenthood is like the new site of gender discrimination," Michelle Budig, a sociology professor at the University of Massachusetts at Amherst, told CNBC.

Budig, who has done similar research on this topic, calls it "the wage penalty for motherhood," and has found that women on average take a salary hit of about 7 percent per child.

Experts say that this other gender gap could be explained by stereotypical assumptions about working mothers. Research has shown that mothers are often seen as less competent and committed at work — whether or not employers consciously realize they have a bias.

"If employers believe, on average, that women with children would be less good workers, then they might discriminate against all women with children," Francine Blau, an economics professor at Cornell University, told CNBC.

Working fathers, meanwhile, benefit from preconceived notions. Says Budig, "Men who conform to expectations of what makes a good man — being a highly educated married father — (are) more valued as an employee."

Do you see these assumptions played out in your workplace?

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