Progesterone also known as P4 (pregn-4-ene-3,20-dione) is a C-21 steriod hormone involved in the female menstrual cycle, pregnancy (supports gestation) and embryogenesis of humans and other species. Progesterone belongs to a class of hormones called progestogens, and is the major naturally occurring human progestogen. CAS No.: 57-83-0 MF: C21H30O2 MW: 314.27 Place of Origin: Jiangsu China (Mainland) Analyse Items Specifications (USP34) Appearance White or creamy white crystalline powder Identification: A: Infrared absorption