Most professional women step off the career 'fast track' at some point in their working life. Family obligations are usually behind a woman's decision to take a temporary leave of absence from her job and career. "They are pulled out by child care reasons,' economist and author Sylvia Ann Hewlett says. "Eldercare is also big, you know, the critical trigger is a mother with Alzheimer's."

She says many men also take some time off, but for very different reasons. "It's usually some kind of strategic career move'" says Ms. Hewlett. "They go back (to college) to get an MBA or something like that."

Ms. Hewlett surveyed more than 2,000 women and a smaller number of men about their experience getting off - and back on - the 'fast track' to career advancement. The result was the report, Off-Ramps and On Ramps: Keeping Talented Women on the Road to Success.

In many companies, women who take a detour on that road are considered not serious about their career, or less ambitious than their male colleagues. Nevertheless, more than one-third of professional women 'off-ramp' for some period of time. Study co-author Carolyn Buck Luce told NBC News, although most of these women want to return to work - and do, they usually have to take a job at a lower, more junior level than the one they left. "It is very difficult to reconnect," said Ms. Luce. "Only about 75% actually are successful in getting back onto the career path, and 40% come back full time.

The results of the survey come as no surprise to Parenting Magazine founder Robin Wolaner. She says that even when they quit to take care of their children, working women have to find a way to stay connected to their career. "If you do think you're going to come back to the workforce anytime in the first decade of your kid's life, staying in it in some way is important," she says. "Carving out even a few hours a week for a part-time position, or freelance work, or something that keeps you in that network, can be very helpful. I worked part-time during my second pregnancy and after my daughter was born. It was actually what people would have considered a step back for me. I wasn't a CEO anymore, but I had a great job, I had a company that allowed me to have the flexibility and the hours I needed."

"You can take a risk early in your career before you've gotten your family obligations, before you're making a lot of money," Ms. Wolaner told VOA. "What would you really have to lose? That's the time to test your wings, and see what you're capable of."

Carolyn Buck Luce says volunteering is another way for off-ramping women to stay connected. "They need to get involved in not-for-profit organizations, so they can continue to hone their leadership skills," Ms. Luce says. "They need to network with other men and women who are involved in the things they're interested in."

The Off-Ramps and On-Ramps report urges corporations to adopt flexible policies and practices that help retain and re-attract highly qualified women. Most importantly, co-authors Sylvia Ann Hewlett and Carolyn Buck Luce would like to eliminate the stigma surrounding a woman's choice to off-ramp for a while.