Dr Caoimhe Hartley

So that was the study of more than 250,000 women.

Like it was enormous done in the States in the 90s.

And they published their first results in 2002, I think, but early 2000s anyway.

And it was flawed.

And the way that those results were interpreted, the way the data was collected has been criticized since, the way that it was kind of portrayed in the media.

That's where a lot of the breast cancer risk and scaremongering came from.

But we still use a lot of the data from the WHI.

And the other interesting thing about the Women's Health Initiative, they used oral oestrogens, they used tablets.

They used Premarin, which is conjugated equine oestrogen.

So it's actually a compound of 30 plus different types of oestrogen.

Pregnant mare's urine.

Pregnant mare's urine.

That's where the name comes from.

And it was heavily marketed back in the 60s.

It was the most commonly prescribed medication between sort of the 80s and 90s in the States.

But that's what they used because that's what was being prescribed at the time, which is fair.

But we now know that Premarin and the oral form of oestrogen is very different.

It's like a totally different medication to what we give through the skin or even the modern oestrogen tablets are different as well.

And the progestin, the thing they used to protect your womb in that study was the thing called medoxyprogestin, which is not as safe a type of progestin as what we use now.

So we're using this data from this really old study