Asked how important the challenge of transgender women is in athletics, Coe said: “I think that the integrity of women’s sport – if we don’t get this right – and actually the future of women’s sport, is very fragile.”
World Athletics has already taken a hard line with DSD (difference of sexual development) athletes like Caster Semenya, forcing them to lower their testosterone levels for six months to compete internationally over certain distances.
The governing body has similar rules regarding transgender athletes, who must keep their testosterone under a certain limit for at least 12 months before competing internationally.
“There is no question to me that testosterone is the key determinant in performance,” said Coe. “If you look at the nature of 12 or 13-year-old girls, I remember my daughters would regularly outrun male counterparts in their class, but as soon as puberty kicks in that gap opens and it remains.
“Gender cannot trump biology. As a federation president, I do not have that luxury. It is a luxury that other organisations not at the practical end of having to deal with these issues have.
“But as far as I am concerned, the scientific evidence, the peer-reviewed work we have done, those regulations are the right approach.”
Asked how he might feel when athletics encounters its first transgender woman winning races like Thomas, Coe suggested it was important to put aside emotion and focus on the scientific basis for the current regulations.
“You can’t be oblivious to public sentiment, of course not,” he said. “But science is important.
“If I wasn’t satisfied with the science that we have and the experts that have been working on this for a long time, this would be a very different landscape.
“If I feel that we’ve got the right processes in place and what we’re doing is, in large part, evidence and science-based, I feel a whole heap more comfortable.
“It’s really difficult to keep the emotion out of this and subjectivity, so we do have to really stick as closely as we can to the science. That’s what we’ve always tried to do when it’s been uncomfortable.”
Coe also called on the International Olympic Committee to implement blanket transgender rules and stop asking individual sports to come up with their own policies. “It is not something you can keep farming off onto the member federations,” he said.
Thomas’ National Collegiate Athletic Association championship victory prompted a protest from three of her beaten rivals, who posed together on a single podium step apart from the winner. One of those defeated swimmers, Erica Sullivan, won a silver medal at last year’s Tokyo Olympics.