Players must be assigned female at birth or have transitioned to female before going through male puberty to compete in LPGA tournaments under new gender policies.

The updated policies would rule out eligibility for trans golfer Hailey Davidson, who missed qualifying for the US Women's Open this year by one shot.

Davidson began hormone treatments when she was in her early twenties in 2015, and in 2021 underwent gender reassignment surgery, which was required under the LPGA's previous gender policy.

The Ayrshire-born player, who now lives in America, had won this year on a Florida mini-tour called NXXT Golf until the circuit announced in March that completing players had to be assigned female at birth.

The LPGA and USGA [United States Golf Association] have said their policies are geared toward being inclusive of gender identities and expression while striving for equality in competition.

"Our policy is reflective of an extensive, science-based and inclusive approach," said LPGA commissioner Mollie Marcoux Samaan.

"The policy represents our continued commitment to ensuring that all feel welcome within our organization, while preserving the fairness and competitive equity of our elite competitions."

The policies, which begin in 2025, follow more than a year of study involving medicine, science, sport physiology and gender policy law.

The LPGA said its working group of experts advised that the effects of male puberty allowed for competitive advantages in golf compared with players who had not gone through puberty.

Mike Whan, the former LPGA commissioner and now CEO of the USGA, said it developed the updated policy independently and later discovered it was similar to those used by swimming, track and field, and other sports.

"It starts with competitive fairness as the 'north star'," Whan said.

"We tried not to get into politics, or state by state or any of that stuff. We just simply said: 'where would somebody - at least medically today - where do we believe somebody would have a competitive advantage in the field?' And we needed to draw a line.

"We needed to be able to walk into any women's event and say with confidence that nobody here has a competitive advantage based on their gender. And this policy delivers that."

The Competitive Fairness Gender Policy for the USGA takes effect for the 2025 championship season that starts with the US Women's Amateur Four-Ball on May 10-14.

Qualifying began late this year, though there were no transgender players who took part.

"Will that change in the years to come as medicine changes? Probably," Whan said. "But I think today this stacks up."

The LPGA Gender Policy for Competition Eligibility would apply to the LPGA Tour, Epson Tour, Ladies European Tour and qualifying for the tours.

Players assigned male at birth must prove they have not experienced any part of puberty beyond the first stage or after age 12, whichever comes first, and then meet limitation standards for testosterone levels.

The LPGA begins its 75th season on January 30 with the Tournament of Champions in Orlando, Florida.