While women earn roughly 97 cents on the dollar of what men make, recent college graduates (those between ages 22 and 27) earn more than men in 29 of 73 majors researched. However throughout the course of a career, this advantage not only disappears, but these women end up behind the pay grade of their male counterparts.
In a blog post, Jason R. Abel and Richard Dietz report on this wage gap, and comment on why it appears. According to their research, the wage gap widens significantly as women and men approach their mid-career:
When we estimate the gender pay gap by major for the mid-career group, the advantage completely disappears in the majors where we found younger women earned more than younger men, and the male wage premium widens substantially across nearly every major.