"The Council has agreed to exclude male to female transgender athletes who have been through male puberty from female world ranking competitions from March 31 this year."
World Athletics president Sebastian Coe said that the decision to exclude transgender women who had gone through what he called male puberty was based on what he said was "the overarching need to protect the female category."
The new rules will also impact athletes with what is known as "differences in sex development," or DSD.
The most famous might be South Africa's two-time Olympic 800-meter winner Caster Semenya, who has XY chromosomes and blood testosterone levels in the male range.
The council vote will require DSD athletes such as Semenya and Namibia's silver medalist Christine Mboma to take testosterone-reducing medication and maintain low levels of the hormone for two years before they are cleared to compete.
That could keep some DSD athletes out of events for 24 months, although Coe said some could apply for a shorter, six-month monitoring period.
"So none of these athletes will be eligible to compete in the World Athletics Championships in Budapest in August. They will be eligible to compete in other events after that six-month period, including the Paris Olympic Games next year if and only if they maintain their testosterone at the required level."
The move banning trans women comes as some claim athletes born male have innate physical advantages over those born female.
"The majority of those consulted stated that transgender athletes should not be competing in the female category.”
The tighter measures around one of the most contentious and divisive issues in sport follow a similar move by World Aquatics in 2022.
Coe said the governing body was "not saying no forever," and announced the formation of a working group, which will be chaired by a transgender athlete, to further study the issue of trans inclusion.
Cyclist Worley blasts World Athletics transgender ban
Cyclist Kristen Worley, the first transitioned athlete to successfully legally challenge the gender policies of the International Olympic Committee (IOC), on Thursday called World Athletics' ban on transgender woman athletes "disheartening and disappointing."
Worley sought to compete for Canada at the 2008 Beijing Olympics but because of health issues related to the IOC's gender verification process, she was physically unable to perform.
She has since become an educator on the topic of transgender athletes and safeguarding women in sports.
"What's happening is the most vulnerable are being excluded from the sport more for political reasons and not based on science and research," Worley told Reuters.
"This has effects not just at the international levels but consequently over communities across the globe including communities in the United States."
World Athletics president Sebastian Coe early on Thursday said that the decision to exclude transgender women who had gone through male puberty was based "on the overarching need to protect the female category."
The tighter measures around one of the most contentious and divisive issues in sport follow a similar move by World Aquatics in 2022.
But Worley said the notion that transgender women athletes are dominating women's sports was nonsense.
"I'm watching all the newsgroups put out images on Twitter with no images of transitioned athletes at the elite levels of the World Athletics because there aren't any," she said.
"So this is purely a political move by Seb Coe and World Athletics to deal with the right-wing issues, political relationships and obviously potential sponsors that are funding World Athletics today."