Progesterone molecule. Computer graphic of a molecule of the hormone progesterone (chemical formula: C21.H30.O2). The atoms are represented as cylinders, and are colour coded: carbon is pink, hydrogen is white and oxygen is blue. Progesterone is one of the most important of the hormones. 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 produced in the ovaries of women and the testes of men. It governs the development of the uterus during pregnancy, and some synthetic variants are used as oral contraceptives.