Here is an article that does a far better job of explaining the situation than I did:

http://www.todaysengineer.org/2011/May/women-in-engineering.asp

The largest reason women leave engineering is due to the work environment and perceived lack of support from colleagues.   

Interesting, but I don't really get some of the distinctions they are making. Women *are not* leaving engineering to spend time with their families, but they *are* leaving engineering because of 60-hour weeks and having to work weekends.

I'm also not sure that stereotype is still valid. It's the romantic image of a technology start-up trying to get a product out before funding runs out, but most engineers won't work in those. Most will work at established companies or in corporate IT, and in those places, the 60-hour week is either rare or non-existent. There may be other things that scare women away from IT/engineering jobs, but there are plenty of those available that do not require that type of having no life.

Yoav