From The Wall Street Journal, "How to Limit Hit From Maternity Leave" by Ben Casselman:
One reason for the gender gap — though not the only one — is that women remain far more likely than men to take time off to raise children.
***Those years out of the workforce can leave women lagging behind in their careers. Census researchers compared the earnings of women who had taken at least six months off work to those without a prolonged gap. After a decade in the workforce, the women with gaps earned 18% less than those with steadier work histories. ***But researchers found that the story was very different when they looked at how long women had been in the same job, rather than how long they’d been in the work force more generally. If two women have held a job for the same amount of time, it makes little difference if one took time off and the other didn’t. ***In a report Tuesday, Census researchers Rebecca Chenevert and Daniel Litwok said the data suggest two conclusions: First, many women start new jobs when they return to the workforce, and effectively start over at the bottom of the totem pole. And second, women who return to the same job are better able to keep up with their peers than those who don’t.