Many more women take time off from work. Many more women work part time at some point in their careers... And our economy exacts a terribly steep price for any time away from work — in both pay and promotions... Entire career paths are closed off. The hit to earnings is permanent... The main barrier [to gender equality] is the harsh price most workers pay for pursuing anything other than the old-fashioned career path. “Women do almost as well as men today,” [Jane Waldfogel, a Columbia University professor] said, “as long as they don’t have children.”... A recent study of business school graduates from the University of Chicago...did find one subgroup of women whose careers resembled those of men: women who had no children and never took time off.... With Australia’s recent passage of paid [parental] leave, the United States has become the only rich country without such a policy.