World Rugby has recommended transgender women should not play in women's elite or international teams for safety reasons, becoming one of the first major world sports to do so.
The governing body on Friday released new guidelines on the participation of transgender women in women's sport, following a "comprehensive, collaborative and transparent" review of existing guidelines.
The review was led by Dr. Araba Chintoh, a former Canada women's international and psychiatrist who was charged with deciding how inclusivity could be balanced with safety and fairness.
Dr. Chintoh described the review as "complex and emotive" but necessary.
"We set out to determine whether it would be possible to maintain inclusion in contact rugby based on the available research and evidence and rugby's unique context of combining strength, power, speed and endurance in a physical, collision environment," she said. "As we progressed through a comprehensive and inclusive review, it became clear that there are compelling evidenced safety considerations which we simply cannot ignore."
The guidelines are recommendations only and are not binding on national unions in their domestic competitions, though they likely will shape policy in many countries.
"As with many other sports, the physiological differences between males and females necessitate dedicated men's and women's contact rugby categories for safety and performance reasons," World Rugby said in a statement. "Given the best available evidence for the effects of testosterone reduction on these physical attributes for transgender women, it was concluded that safety and fairness cannot presently be assured for women competing against transwomen in contact rugby.
"As a result, the new guidelines do not recommend that transwomen play women's contact rugby on safety grounds at the elite and international level of the game where size, strength, power and speed are crucial for both risk and performance."
The recommendations "do not preclude national unions from flexibility in their application of the guidelines at the domestic (or) community level of the game. Transmen are permitted to participate in men's contact rugby."
World Rugby said it was committed to regularly reviewing the guidance, taking into account new evidence or research.
Chairman Bill Beaumont said rugby was a "welcoming and inclusive sport."
"While this has been a difficult decision to make, it has been taken following comprehensive consultation and engagement and for the right reasons, given the risk of injury," he said. "That said, we recognize that the science continues to evolve, and we are committed to regularly reviewing these guidelines, always seeking to be inclusive."
