Women with young children often discover that child care costs eat up much of what they earn. If they’re married to a big earner in a high tax bracket, they could lose most of the rest of their wages to high marginal tax rates.

But advising them to quit working is short sighted, two Certified Financial Planners suggest in the most recent issue of the Journal of Financial Planning.

Jerry A. Miccolis and Marina Goodman note in “Advising Married Women on Investing–in Themselves” (may be restricted to FPA member access only) that child care costs usually drop when the kids enter school while the mother’s income typically rises over time. Stopping out, meanwhile, often leads to lower lifetime earnings. The authors suggest women view those early years, when they’re working for not much financial gain, as an investment in their future–sort of an extended internship, if you will. They write:

“[W]ork experience leads to career advancement, which could have a quantum-level impact on her financial future. Say a woman spends five years working while getting no financial benefit due to taxes and child care costs. Her youngest then enters school and suddenly child care costs plummet. After five years of experience, she may get promoted and now her income may be $75,000. If, instead, she was just starting out at that point, she would be earning $50,000. (We’re ignoring inflation in this simple example—it would, of course, merely magnify the effects.) The difference is not $25,000. It is more like being an entire professional level higher for the next 30 years. Over the course of a career it can be the difference between middle management and eventually being in the C-suite.”

The authors note that “A woman’s ability to earn a decent salary is the most comprehensive insurance policy she can have.” Staying employed, even part time, and keeping up any professional credentials can help her family if her partner loses a job, becomes disabled or suffers a business setback. It can also be an insurance policy for her in the far greater risk of divorce:

“Even among upper-income families, many women would still experience a significant decline in lifestyle upon divorce, especially if they have no means of supporting themselves. The risk that a woman will get divorced is greater than the sum of the risks of her husband’s premature death, disability, or just about any other financial catastrophe all put together.”

This information may be most relevant for the kinds of women financial planners are most likely to advise: college-educated women with careers, rather than jobs. The price for stopping out may be less if you’re in a low-wage, low-skilled job rather than one where significant financial advances are possible. But any parent contemplating time away from work should be looking at the longer term financial picture, and those who choose to stay home should make sure they have significant savings to help offset their greater financial vulnerability.