If they look at the data I have provided them in my last dozen or so projects they will see that there is no difference whatsoever in the pay for the same work with the same experience. That is definitely not what they want the data to show.
There are actually a number of metropolitan areas that show young women without children earn slightly more than their male counterparts in a number of professional areas.
The income gap shows up after they have children, but never occurs for those who don’t have kids.