The world governing body for swimming, FINA, announced on Sunday that it had voted to restrict trans athletes from participating in elite women’s competitions. The policy, which takes effect on Monday, requires trans swimmers to have completed their transition by the age of 12 to compete in women’s races and keep testosterone levels below 2.5 nanometers. per liter. It effectively excludes most trans women from top swimming events, including the Olympics. The International Olympic Committee postpones to the federation of each sport to determine the eligibility of the athletes. FINA is working to create an “open” category for swimmers whose gender identity is different from their gender. The decision passed with 71 percent of the vote by members of the 152 eligible national federations at a conference held during the World Cup in Budapest. “FINA’s approach to this policy has been comprehensive, science-based and inclusive,” Brent Nowicki, FINA’s chief executive, told the BBC. “Most importantly, FINA’s approach emphasized competitive justice.” The rules come three months after Leah Thomas of the University of Pennsylvania became the first openly trans woman to win an NCAA Division I swimming title, finishing first in the 500 yards freestyle. Her rise has intensified the debate over the position of trans swimmers in the sport. Thomas recently said she hopes to compete in the 2024 Olympics in Paris. Hundreds of swimmers signed a letter of support for Thomas and all trans and non-binary swimmers. But some of Thomas’s teammates and their parents wrote anonymously that while supporting Thomas’s move, they felt that her competition against other women was unfair. FINA plans to use the next six months to create the open class category. “FINA will always welcome every athlete,” said FINA President Husain Al-Musallam. “Creating an open category will mean that everyone has the opportunity to compete at the elite level. This has never happened before, so FINA should lead. “I want all athletes to feel involved in being able to develop ideas during this process.” The decision is a blow to trans athletes and their supporters, including former Harvard swimmer Schuyler Bailar, the first transgender man to compete in a NCAA I-class sport. announcement. “This decision requires trans girls to go before the age of 12, but the United States has seen nearly 100 bills banning trans children from playing youth sports and criminalizing transitional resources for children, making it impossible for them to play sports with any capacity, “Bailar added. is a friend and advisor to Thomas. “FINA’s decision does not safeguard the integrity of women’s sport – it imposes harmful policing on the female body and the continuing degradation of other trans people who are already experiencing mass discrimination in this world.” Athlete Ally, an LGBTQ advocacy group that wrote a letter of support for Thomas in February, also disagreed with the policy. “FINA’s new eligibility criteria for trans athletes and transgender athletes are biased, harmful, unscientific and inconsistent with ILO 2021 principles,” she tweeted. “If we really want to protect women’s sports, we have to include all women.” Sharon Davis, a former British swimmer, wrote on Twitter her support for the FINA decision. “I can not tell you how proud I am of my sport; I do science, I ask athletes / coaches and I defend the fair sport for women,” she wrote. “Swimming will always welcome everyone no matter how you identify with them, but justice is the cornerstone of sport.” Swimming is one of the few sports that has recently introduced stricter restrictions on trans athletes. On Thursday, the governing body of cycling, the International Cycling Association, extended from one to two years the time riders who have a transition race must wait before competing.