She's worked hard, paid her dues and established her career. But once she has children, wham! For too many women, motherhood means a body blow to her salary. Even when controlling for factors like career choice and hours spent, “researchers generally find that moms earn lower hourly wages than women who are not moms,” says Kate Krause, professor of economics with the University of New Mexico. According to Krause’s research, moms of one child earn 7 percent less than women without children. Have two children? Then the average working mother's salary is a whopping 14 percent less.

That’s in addition to the existing “gender penalty,” which finds women still earning only 75 cents for every dollar a man earns, Krause notes. To minimize the “mommy penalty,” experts recommend the following strategies:

Address it  The first step is knowledge, says Claudia Goldin, a Harvard economist who co-authored the 2010 study “The Career Cost of Family.” Before going on maternity leave, Goldin advises women to ask: “Are there large penalties for taking time off? Is there substantial loss in income for part-time work?” Alternately, she says, see if your employer has a division or function that’s more suitable for flexibility, while allowing you to advance.

Prove yourself first  Make yourself invaluable — service important clients, be someone’s right hand, connect yourself with the core mission — before you have children. Employers recognize that it’s a huge competitive advantage to keep proven talent rather than recruit someone new. “Women who have children and come back to the same employer after a period of leave have much lower or no penalty, whereas those who stay out for a period of time and then start someplace new have the largest penalties,” says Jane Waldfogel, professor of social work and public affairs at Columbia University, who has authored numerous studies on women’s earnings and parenthood.

Come back when you’re ready  There isn’t a magic age (a.k.a. kindergarten) when work-family conflict resolve itself for working mothers (or fathers, for that matter). “Waiting until your child is older to return to work just delays the penalty; it doesn’t eliminate it,” says Krause. Research has shown that moms take the wage hit immediately. Jumping back in as soon as you’re ready gives you more time to rebuild.

Think M.D. not MBA  Some professions penalize women a lot — and others are relatively forgiving. “The penalty for ‘any job interruption’ is substantial for MBAs,” writes Goldin in “The Career Cost of Family” which compares how MBAs, MDs and lawyers fare in terms of wages and parenthood. (Women MBAs with children, for instance, saw their pay drop 41 percent relative to male MBA earnings.) By comparison, women doctors across many specialties saw a smaller loss (16 percent versus men) and were more able to pick up professionally where they left off following a break to raise children.

This article was featured in the July 2011 issue of Working Mother Research Institute’s email newsletter, Working Mother Research Institute Essentials. To read additional stories from that issue, see the related content section above. To subscribe to Working Mother Research Institute Essentials, sign up now.