You can find studies on this. Treated as a group women are more likely to trade things like extra time off and flexible hours for salary.
It's very rational when you consider that it's consistently been shown that women are more likely (notice I said likely) to place a higher value on non-monetary compensation.
Yes, for some. Come to think of it, spending time with the kids is probably the number one reason men downshift (by choice) as well.
What is complicated and not fully understood by me is how accurately we have accounted for women who voluntarily choose to downshift in all of the 'glass ceiling' statistics. I think that the glass ceiling is very real, but I just wonder how trustworthy the stats are. It's complicated.