Progesterone hormone molecule. Computer model showing the structure of a molecule of the hormone progesterone. Progesterone is produced in the ovaries of women and the testes of men, and is one of the most important hormones in the human body. It is the biological precursor of the oestrogens (female sex hormones) and the androgens (male sex hormones), as well as other steroid hormones . It is involved in the female menstrual cycle and governs the development of the uterus during pregnancy. Some synthetic variants of progesterone, called progestins, are used as oral contraceptives. Atoms are represented as spheres and are colour-coded: carbon (black), hydrogen (white), and oxygen (red) - with the bonds between them as rods (silver).