Certainly not a universal, but I seemed like the men, especially the American ones, did better in the hands on engineering classes. The foreign students and women were relatively less comfortable with the practical parts. But it has been many years since I was in school.
The same mathematics concepts were being taught, but in a way that would appeal and allow women to thrive, Klawe said.
So, what is girl math like?
So, in my limited anecdote - a 90% washout rate for women, vs 70% for men.
IMO - and with no scientific evidence, or even a hint of how the female psyche works..... I think that most of the women in the class couldn't handle being "average". Once the first semester was over, and all of the people who didn't belong in engineering to start with had quickly departed, those who were left were all fairly sharp, regardless of which bathroom they used.
As an engineer I'm sure that you know this, pulling a "B" average in engineering courses is pretty darned good. I took a few required classes where I got a 'C', and got the heck out. (Solid State Physics? Phew.) However, for the women in my EE classes who had been at the top of the school with Straight A's for all their lives, they couldn't handle the sudden mediocrity. "C's" weren't good enough, they let stress eat them up, and they usually would wind up headed for easier disciplines.
Also, FWIW, most of the engineering washouts - across the board, all genders and disciplines - wound up in either "Business" or "Education". I think this probably says something, but I'm not sure what.