For anyone interested, Freakonomics explored[1] this in detail and their conclusions were pretty similar.

It included an interview from Claudia Goldin and her research[2] which was quite in-depth.

[1] http://freakonomics.com/podcast/the-true-story-of-the-gender... [2] [PDF] http://scholar.harvard.edu/files/goldin/files/gender_equalit...