Swimming's world governing body FINA has voted overwhelmingly in favour to ban transgender athletes from competing against women in elite races.
The new policy could instead see transgender athletes compete in an 'open' event if they did not complete their transition by the age of 12 after a 71% vote from member federations at the Extraordinary General Congress.
Athletes will not be permitted to compete in women's elite events if they had started to go through male puberty before transitioning, and FINA president Husain Al-Musallam has insisted that "competitive fairness" must be protected with the new policy.
"We have to protect the rights of our athletes to compete, but we also have to protect competitive fairness at our events, especially the women's category at FINA competitions," Al-Musallam said in a statement.
"FINA will always welcome every athlete. The creation of an open category will mean that everybody has the opportunity to compete at an elite level.
"This has not been done before, so FINA will need to lead the way. I want all athletes to feel included in being able to develop ideas during this process."
Three months ago, Lia Thomas won the women's 500-yard freestyle at the NCAA Swimming Championships, becoming the first transgender athlete to win the highest level of US College title.
University of Pennsylvania swimmer Thomas started hormone replacement therapy in 2019, and her victory sparked a global debate surrounding transgender athletes in sports.
