A group of 17 House Republican lawmakers, led by Rep. Claudia Tenney from New York, is urging the National Collegiate Athletic Association (NCAA) to prohibit biological men from participating in women’s sports.

Under current NCAA rules, biological male athletes who self-identify as women can participate in women-only sports competitions if they take testosterone suppressants and bring down their testosterone levels to the maximum allowed for a specific sport. The athletes must provide documentation several times per year to show their testosterone levels.

The lawmakers penned a letter to NCAA President Charlie Baker that asks him to limit participation in women-only sports to biological women. They sent the letter to Baker about a week after a smaller college athletics association — the National Association of Intercollegiate Athletics (NAIA) — unanimously voted to restrict most women’s sports to biological women and forbade biological males from participating in such competitions.

“We must protect the opportunity for women and girls to compete and succeed in athletics fairly,” Tenney said in a statement.

“While I applaud the NAIA’s recent decision to ban biological men from women’s sports, I am deeply disturbed that the NCAA is ignoring the facts and failing to do the same,” Tenney added. “Women fought hard to earn the critical protections of Title IX, and we must continue to protect these opportunities for generations to come. I am dedicated to defending the future of women’s sports and providing a level playing field for all female athletes.”

The letter praises the NAIA decision, stating it “appropriately recognizes the natural advantages that biological men have in certain athletic competitions.” It asks Baker “to reconsider [the NCAA’s] current policy that allows biological males to deprive women of a fair opportunity to compete and achieve athletic success.” 

“All women in NCAA-affiliated schools should not fear having their athletic accomplishments minimized by biological males, as happened in the 2022 NCAA 500-yard freestyle event, with Lia Thomas, a biological man, taking the championship over Emma Weyant,” the lawmakers wrote. “This cannot be allowed to ever happen again. The NCAA must follow the NAIA’s lead and prohibit biological males from competing in women’s sports.”

In the letter, the lawmakers cite a 2022 study that found that biological men have certain physical advantages over biological women, even after taking testosterone suppressants. The study, titled “Transwoman Elite Athletes: Their Extra Percentage Relative to Female Physiology,” noted that many anatomical sex differences that are driven by testosterone are not reversible. 

“The NCAA’s current transgender policy fails to take these scientific facts into consideration,” the lawmakers said.

The NAIA is the governing body for about 250 colleges and universities. The NCAA represents more than 1,100 colleges and universities, which includes dozens of Catholic institutions. The NCAA rules do not require Catholic institutions to permit biological men on the women’s teams; however, they may be forced to compete against colleges and universities that include biological men on their teams. 

About two dozen states have passed legislation to restrict women’s and girls’ sports to only biological women and girls in recent years. Still, more than half of the states in the country allow biological men who identify as women to participate in women’s sports.