The International Olympic Committee announced its updated guidelines for transgender athletes on Monday. In the past, the IOC required that transgender athletes undergo sex reassignment surgery and hormone therapy to participate, but Olympians can now take part in the Games without undergoing the surgery. The document that outlines the new guidelines states, "To require surgical anatomical changes as a pre-condition to participation is not necesssary to preserve fair competition and may be inconsistent with developing legislation and notions of human rights."
The guidelines differ for trans male athletes and trans female athletes — athletes who transition from female to male are eligible to compete "without restriction." However, those who transition from male to female "must demonstrate that their total testosterone level in serum has been below 10nmol/L for at least 12 months prior to competition." Their testosterone levels may also be tested regularly, and an athlete's declaration that her gender identity is female cannot be changed "for sporting purposes" for a minimum of four years.