World Athletics has banned transgender women from competing in female track and field events.
"The council has agreed to exclude male or female transgender athletes who have been through male puberty from female world ranking competitions from March the 31st this year," the governing body's president, Sebastian Coe, said on Thursday.
No such athletes currently compete at the highest elite levels of track.
Coe said World Athletics had discussed the issue with the International Olympic Committee, national federations and trans groups before making the decision.
"The majority of those consulted stated that transgender athletes should not be competing in the female category," he said.
Step taken to 'protect the female category'
Coe said the decision to exclude transgender women was based "on the overarching need to protect the female category."
"Many believe there is insufficient evidence that trans women do not retain advantage over biological women and want more evidence that any physical advantages have been ameliorated before they are willing to consider an option for inclusion into the female category," Coe said.
Coe added that World Athletics would form a task force to study the issue of trans inclusion.
Swimming's world governing body, FINA, voted last June to bar transgender women from elite competition if they had experienced any part of male puberty
German trans organization oppose changes
But, speaking to DW, Gabriel Nox Koenig from German advocacy group ‘Bundesverband Trans* eV’ (roughly translated as the Federal Association for Trans people), said this line of reasoning is nonsensical.
"There was no attempt here to enable fair competition, but rather to specifically exclude trans women and non-binary people who were born male," Koenig told DW. "While it is theoretically possible to use puberty blockers to delay puberty in trans and non-binary youth, in practice the number of those who have access to this treatment is very small. So the World Athletics Federation's regulations are basically unobtainable for anyone."
Koenig also said such a ruling may discourage young trans people from taking up sport. "Trans and non-binary people have a lot of discriminatory experiences in sports, whether at school, in amateur sports or in competitive sports," says Koenig. "Most of them therefore decide very early in life against organized sports. And now the new regulation makes it clear once again, especially to trans women, that they are not wanted in sports and should not even start with it."
DSD athletes must reduce testosterone levels
The athletics council also voted to adopt new regulations that could keep Caster Semenya and other athletes with differences in sex development (DSD) from competing.
DSD athletes have male testes but do not produce enough of the hormone Dihydrotestosterone (DHT) that is necessary for the formation of male external genitalia.
Coe said 13 athletes are expected to be affected by the council's updated DSD rules, including Semenya, a two-time 800 meter Olympic champion.
In order to compete at next year's Olympics, Semenya would have to undergo hormone-suppressing treatment for six months, something she has said she will never do again, having undergone the treatment a decade ago under previous rules.
Edited by: Matt Pearson