By now the statistics are well-known, if still unsettling: Women make up less than five percent of the chief executives at the biggest corporations. Just under 20 percent of directors at S&P 500 companies are female. Only 18 percent of computer science degrees are awarded to women, and under 30 percent of the science and engineering workforce is female.

To try and improve those consistently low numbers, high-profile initiatives have been taking aim at them, from the Rockefeller Foundation's initiative to get 100 female CEOs in the Fortune 500 to Melinda Gates' decision to dedicate more resources to getting women into tech.

Yet while attention has been showered on these important, widely covered problems — the lack of women in leadership positions, and the rarity of women in STEM fields — there's another pipeline problem that doesn't get nearly as much time in the spotlight. And while it's persistent and pervasive, it stands to be fixed much more easily than the others.

For every 130 men who are promoted from the entry-level ranks to manager, a new report showed this week, just 100 women are promoted at similar levels. That revealing number, included in the comprehensive annual study on women in the workforce by McKinsey & Co. and, the organization founded by Facebook executive Sheryl Sandberg, is a reminder of the yawning gap that men and women face even at the earliest stages of their careers.

First reported in the Wall Street Journal, the study gathered data on promotions and careers of employees at 132 companies and surveyed some 34,000 men and women about their careers. It showed that men are 30 percent more likely than women to see a promotion at this initial jump up the ladder, noting the gap is "the largest" at this early first stage.

"For us it was a real surprise — to see that this first promotion is so critical and there’s such a disparity," said Alexis Krivkovich, a partner in McKinsey's San Francisco office, in an interview. “The public narrative has focused on left of the pipeline — Do we have women with the degrees necessary? — and the right of the pipeline — Do we have women in senior roles? — but it’s underemphasized what happens to women early in their careers.” 

What's driving the gap? Given all the research that's been done on the effect of motherhood on hiring and wages for young women, one might think a change in family roles is behind it. But that doesn't appear to fully explain it, Krivkovich said. What the new data shows is that both men and women cite family balance in equal numbers as their top worry when asked about why they do or don't want the next promotion. That suggests that "this is not just about family concerns," she said.

The shift from entry-level into managerial jobs typically comes about five to six years in, Krivkovich said. That's before the mid-career years when heightened work expectations and the increased family demands of children and aging parents often really take their toll. Conventional wisdom about women's careers, she said, "suggests that’s the real pinch point, but the fact that there’s such a pronounced gap right at the outset suggests to us there’s more going on here that companies need to address." 

Meanwhile, the responses of men and women revealed two very different experiences: In the survey, women said they get consulted on fewer important decisions, didn't get as many stretch assignments and didn't feel they could participate equally in meetings. They also had different experiences with feedback: While men and women asked for feedback in similar numbers, and managers thought they gave it out to both, women said they actually received the kind of critical feedback that helps them advance much less often than men.

Krivkovich said unconscious bias is a culprit: "I think bias is a huge piece of it. I think a lot of companies think they’ve put in the training, the policies, and the leadership engagement. What the data suggests is those are important steps, but somewhere in there you haven’t yet solved for the bias underneath that’s getting in the way." 

This is hardly the first time that researchers have seen a big gap in how often young women see early career promotions. For instance, Catalyst, the nonprofit research firm, reported back in 2010 that even when looking at graduates of elite MBA programs, women start out behind their male peers. Although they adjusted for things like work experience, industry and region, men were still more likely than women to hold managerial jobs in their first post-MBA gigs. 

It sounds like little has changed. Sure, more gender diversity in the senior ranks could help change corporate cultures so more young women get their first managerial jobs. And having more women with the right degrees will help improve the pool of entry-level women for promotions. But it works the other way, too: If women's careers are slowed down early on, or if all those newly minted STEM grads don't see their early work rewarded in equal favor, the numbers at the top aren't going to improve anytime soon, either.

Perhaps the best argument for why the gap in early promotions should get more attention is that it could be the easiest to fix. Krivkovich noted that it could take decades to get people into the right degrees, and years for companies to improve the number of women at the top if they haven't built the right internal pipeline. Yet correcting the promotion gap is usually about better execution of the programs and policies they already have in place. "There's a huge opportunity," she said. "The first promotion? Companies can solve that today." 

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