Transgender women over a certain height and weight may be risk-assessed before they can play English domestic rugby under draft Rugby Football Union plans.
The proposal would add to the existing requirement for trans women to suppress hormones for a year before they play.
Global governing body World Rugby said in October that it "does not recommend" transgender women play contact rugby.
The RFU says its proposals aim to "strike a balance between fairness, inclusion and safe participation".
"It's important to consider the individuals involved and the sense of community and acceptance that our transgender players tell us rugby provides for them," the English governing body added.
"The RFU has considered alternatives as part of its review, including both more and less restrictive measures, but having considered such alternatives, believes the criteria proposed in the policy are the most appropriate for domestic rugby union in England at this time."
Measures included in the draft policy include:
- Transgender women players over 90kg (14st 2lb) or taller than 170cm (5ft 7in) may be assessed by an RFU coach or staff in a training environment to check if they have "a material performance advantage" or pose "a safety risk to other participants which is above the level presented by cis women players [players whose gender matches their assigned sex at birth]". The weight and height thresholds are based on "90% of cisgender women in the UK being below those measurements".
- Transgender women will also be asked to provide details on their previous sporting background.
- Transgender male players will be asked to sign a declaration that they understand the risks of playing men's or boys' contact rugby.
- Non-binary players may participate in the gender category they feel most comfortable with, but must meet the same conditions as transgender players if that is different from their assigned sex at birth.
The RFU is inviting consultation on the proposed changes, and says it will "continue to monitor relevant new research and data" into the issue.
Transgender players cannot currently play without prior approval from an independent three-person panel, which reviews their eligibility on a case-by-case basis.
Over the past three years, the RFU has received 39 applications from trans men, seven from trans women and four from players identifying as men but wanting to continue playing women's rugby.
How did we get here?
The RFU's suggested change in policy follows World Rugby, the game's global governing body, altering its stance.
In October, World Rugby became the first international sports federation to say transgender women should not compete at elite and international level in the women's game.
Previously, World Rugby had followed International Olympic Committee policy requiring transgender women to suppress testosterone levels for at least 12 months before competition.
However, World Rugby allowed national unions to be flexible in how they apply guidelines and recommendations, prompting the RFU to start its own review.
The RFU allows girls to play alongside boys until they are divided by sex from under-12 level upwards.
The Welsh, Scottish and Irish rugby unions all follow Olympic guidelines, using hormone levels as the deciding factor in the inclusion of transgender women players.
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