Trans women have been banned from competing in the category that aligns with their gender identity by the Welsh Rugby Union (WRU).
The new policy was enacted after a vote by the WRU board on 7 September – despite there being no openly trans players in professional Welsh women’s rugby.
“Contact rugby for players in the female category is limited to those whose sex was recorded as female at birth,” the guidance states.
A statement from the WRU acknowledged the change in its policy, which previously “allowed for participation in women’s game for transgender women” after the outcome of a medical process was determined.
It added that it is “committed to an ongoing review of the policy as new evidence, research and insights become available”.
The WRU said the decision was “based on the best current medical and scientific evidence and in line with World Rugby guidance”.
It cited advantages in strength and physique obtained during puberty, which it said remained “significant and retained” even after testosterone suppression.
Its new policy has been implemented with immediate effect.