A structured overview of progesterone as a tissue-signal hormone

Progesterone is often described as a female sex hormone or a pregnancy hormone.

That is true, but incomplete.

Progesterone is better understood as a tissue-signal hormone. Its effects depend on timing, dose, route, receptor expression, tissue state, inflammation, local metabolism and whether the target tissue can respond appropriately.

This is why progesterone can appear simple in theory but complicated in practice.