So what qualifications are required to run in a women's race?
At the levels of elite competition, registering under one's identified gender has been more of an issue for transgender athletes who were assigned male at birth. The Olympics revisited its guidelines ahead of the 2016 Rio Games allowing athletes to participate without gender confirmation surgery, but requiring female transgender registrants to prove their testosterone levels did not exceed a certain amount.
Also, the use of the term "assigned at birth" is really offensive to me. Unless you were born a hermaphrodite, you are classified as male or female buy your reproductive organs – not assigned.
Organizers behind the Boston Marathon have expressed support for transgender people to race under the gender they identify, but transgender runners still face hurdles when it comes to registering.