Progesterone

Progesterone (P4) is an endogenous steroid and progestogen sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species. It belongs to a group of steroid hormones called the progestogens, and is the major progestogen in the body. Progesterone has a variety of important functions in the body. It is also a crucial metabolic intermediate in the production of other endogenous steroids, including the sex hormones and the corticosteroids, and plays an important role in brain function as a neurosteroid.

In addition to its role as a natural hormone, progesterone is used as a medication. In transfeminine individuals, it is mainlyused to help with breast growth, mainly to reach later Tanner Stages. Sometimes, it is used as a way to suppress testosterone levels in the blood.

It is highly debated if progesterone works in AMAB people, some endocrinologists saying that it does nothing but create breast cancer, others, such as Dr. Powers, saying that it is essential to develop the breasts fully.