Dr. Mary Claire Haver

And it's the drop in progesterone that induces lactation.

Now, progestins, and how are they different than progesterone?

So progestins are synthetic progesterone.

Essentially, it is a molecule that has been created... Developed to prevent a pregnancy with lots of side effects.

Exactly.

So that was how they were originally developed.

They were part of the combined hormonal contraceptives, and they were at pretty high doses, just like the estrogen component, very high doses.

A lot of the early studies and side effects are from those high doses.

But progestins, each of them has a little bit of a different formulation.

And remember, they're designed to target the progesterone receptor.

They target it better than natural progesterone, at least the progesterone that we take exogenously, which means we take a pill, right?

So if we took natural progesterone, it would dissolve immediately in our body.

So the way that we take natural progesterone is we micronize it.

We turn it into this small molecule that will last longer so that we can get progesterone stimulation in our body.

Progestins work better, to be honest, on the progesterone receptor in the uterus specifically.

So they're better at preventing abnormal bleeding.

They work better in the brain.

It's incredibly hard to take enough natural progesterone to suppress ovulation.

Yeah.

So that's why the progestins are much better at telling the pituitary, hey, I've got progesterone, I released an egg, don't release one, right?