Dr. Mary Claire Haver

Why?

Because ethanol estradiol is a more potent form that works better for the goals of birth control.

And this is the key, is that the purpose of birth control is to suppress ovulation, prevent an egg from being released so you can't get pregnant.

Now, you can do that with natural estrogen, natural estradiol.

The issue is that the number one side effect of birth control pills is bleeding.

And it is bothersome and people stop taking them because of it.

Ethinyl estradiol actually is very good at stabilizing the lining of the uterus and helping to prevent bleeding while also feeding back on the pituitary.

That's the part of the brain that tells the ovary to get an egg ready.

Ethanyl estradiol feeds back, tells it not to do that.

It's not the primary way birth control works.

It's the progestin we'll talk about, but it feeds back and then it also stabilizes the lining very well.

Yes.

So exactly.

It's that lock in the key.

So imagine that you now have this lock that has a key that will not get off.

So it is incredibly attracted to the receptor.

It stays on it.

But it doesn't even just do that.

When it's staying on it, you can imagine that there's lots of different bodily functions that respond when there's estrogen in the system.

So the main one we think about is the liver.