Before reaching for explanations to reinforce hackneyed oppression tropes, there might be a more economic reason women leave engineering and STEM fields in general. Engineering is about developing skills, and all technical skills have a relatively early inflection point of diminishing marginal returns on effort. Engineering has a high barrier to entry, and women who are in engineering are necessarily in the 80th perc…
You mention kids, but that's basically a concern in any field in the US, because FMLA requirements are a joke. Plus many men in engineering (where parental leave is often much longer than FMLA requirements) take long paternity leave, and many women choose not to have children anyway.
So what exactly is it about engineering that makes it the smart move for women to leave the field but not men? Or what is it about women that makes them recognize that it's the smart move when men don't see it?
I'm not saying that your assertion is strictly wrong, but I am saying it's not interesting. If women are leaving engineering because of entrenched sexism, that might well be the "smart move" for them. But this isn't a useful insight because the underlying problem remains the entrenched sexism.