Progesterone, also known as P4, is a reproductive hormone involved in the menstrual cycle. Influencing what is known as the “luteal phase”, it helps prepare the uterine lining for implantation. If implantation does occur, progesterone helps maintain the integrity of the endometrium, helping to secure the new pregnancy. It also plays a role in the development of an embryo.
Where does progesterone come from?
The first half of the menstrual cycle is referred to as the “follicular phase”.