In the moody alcoves of a lobby bar in Chicago in 2021 over French 75s, Dr. Louise King, a gynecologic surgeon, and Katie L. Watson, a bioethics professor, found themselves in conversation about a topic that had long frustrated them both: Female surgeons are consistently underpaid compared to male surgeons, even after accounting for specialty, rank, age, and other factors.  What troubled them even more was how the pay gap compounded in King’s own field. Surgeons who perform procedures that are specifically for women, like gynecological surgeries, are paid less for their services than...