[AbiDrew85]

If only progesterone can suppress ovulation, why do most birth control pills have both E and P? I know there are BC's than only contain a progestin, like the depo shot, but then why do combo BC's even exist? I know this doesn't sound like it has anything to do with BE, but I feel like I'm missing a key piece of info.

I'll admit I don't really understand BC, but my best guess would be that in some cases, progestin-only caused too many problems and they found that by balancing the E, the problems lessened.

Keep in mind that synthetic progestins are often tens to hundreds of times more competitive AND volatile than natural progesterone... If you don't balance that, just think of the problems that could be had if your body fails to do it for you.