In March, Lia Thomas made history in the United States as the first transgender woman to win an NCAA swimming championship. She won the 500-yard freestyle.
Other sports have also been examining their rules.
On Thursday, cycling's governing body updated its eligibility rules for transgender athletes with stricter limits that will force riders to wait longer before they can compete.
The International Cycling Union (UCI) increased the transition period on low testosterone to two years, and lowered the maximum accepted level of testosterone.
The previous transition period was 12 months but the UCI said recent scientific studies show that "the awaited adaptations in muscle mass and muscle strength/power" among athletes who have made a transition from male to female takes at least two years.