A recent study by Sylvia Anne Hewlett, founder of the nonprofit Center for Work-Life Policy and Carolyn Buck Luce, a global managing partner at Ernst & Young, showed that 37 percent of women have opted out of their careers at some point; 43 percent for women with children. Only 5 percent of highly qualified women are looking for ways to rejoin the companies they left. The study was discussed by the authors in an article in the March 2005 Harvard Business Review. "If ever there was a danger signal for corporations, this is it," write Hewlett and Luce.

    Anne Berkowitch, co-founder and CEO of SelectMinds, a New York consulting firm that creates and manages corporate alumni networks, says more and more companies are trying to devise work arrangements attractive enough to make these valuable women come back. Alumni networks, Berkowitch says, are the next evolution of women’s networks, which were originally designed to mimic "old boys" networks and help women further their careers.

    "Now women can access other women who left the company in similar situations and find solutions that will work for them, be that a job share or coming back as a consultant." she says. "And being part of an alumni network is a great way to keep these women connected to the company."