above chart shows the pay received by men and women only one year after college graduation -- long before any time is taken off for any reason.
If the pay is so unequal right out of college (where women make only from 77% to 88% of what their male counterparts earn for the same work), then it becomes obvious that the inequality is an endemic part of the system -- and cannot be justified by anything the women do (or don't do). Like it or not, unequal pay translates directly into unequal rights -- whether the lower pay is given to women, minorities, or for some other equally ridiculous reason.
This is just another way in which the Republicans don't believe in fairness. All people who have the same education and qualifications, and are doing the same job, should receive equal pay. To pay a person less because of sex or race is nothing less than theft.
Why do the Republicans continue to oppose equal pay for equal work? Because they have decided that corporate profits (and corporate campaign donations) are more important than constitutionally-guaranteed equal rights -- and that is just wrong.