Hello and welcome to Morales.

We're the programme that demystifies data and simplifies stats.

I'm Lucy Proctor.

This week we'll be taking a dive into one of the most controversial numbers stories around.

Sports bodies worldwide face a challenge.

How can they maintain fairness in women's competitions while including trans women?

Now a trans swimmer in America's elite college competition

has brought that question into sharp belief.

The historic performance is of a swimmer at the University of Pennsylvania

are getting a lot of attention.

Is smashing records in the US women's competition?

Because she keeps winning.

Finishing one race to full 38 seconds ahead of the closest rival.

Leah Thomas, who was born male,

competed for three seasons on the men's team for the University of Pennsylvania

and began transitioning in 2019.

Now racing in the female category for her first season

she swam the fastest times in college athletics in the 200 and 500 freestyle

and is now ranked number one for these events.

While some hail this as a breakthrough for trans visibility

others see Leah Thomas's inclusion in female races as unfair

and that's because of the changes that testosterone produces in male bodies during puberty.

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