Dr. Mary Claire Haver

So that's medroxyprogesterone acetate.

We're all very familiar.

Yes.

This one is the most potent at the level of the uterus.

So it's probably the best, at least in the commercially available doses.

Northendrone acetate is actually a little more potent, but we use higher doses of Provera.

So it works very well to control bleeding.

That's why it was used for so long.

Depomidroxyprogesterone acetate, that's Depo-Provera, is like a huge dose that we use for birth control.

So Provera works very well at suppressing ovulation, blocking the effect of estrogen in the uterus.

But it is unique in that it stimulates the glucocorticoid receptor.

And that's why people get so bloated on it.

So when you see people that have different reactions to different progestins, that's why.

And medroxyprogesterone acetate in some studies looks like it could stimulate breast cells in a way that makes you concerned that it could increase the risk of breast cancer.

Now, I've talked about what the WHI really showed in terms of breast cancer, but it's

But Provera was what they used in that study.

It's always been considered the villain when it comes to things like breast cancer risk.

But all the progestins are going to affect breast cancer cells a little different.

And natural progesterone seems to be the least likely to stimulate breast cancer cells.

And the data we have, we only have five years worth of any natural progesterone.