Well before the glass ceiling, women run into obstacles to advancement. Evening the odds early in their careers would have a huge impact. Despite near-parity in entry-level numbers, women are outnumbered almost 2 to 1 by men in first-level manager jobs that are the bridges to senior roles.

https://www.wsj.com/articles/where-women-fall-behind-at-work-the-first-step-into-management-11571112361