I think it's really important to use a different analogy than a pipeline, because “pipeline” gives you the sense that people are just dropping out because of gravity. In some cases, they're actively pushed out. In the cases of engineering and medicine, there are reports—we haven't done them here in Canada, but in the United States—that there is a high degree of gender-based harassment, including sexual harassment. Women are pushed out. The harassers stay; the women students move. That's incredibly compounded for faculty who are Black or indigenous.
Things like the sticky floor and the glass ceiling are much more apt analogies than the pipeline.