This document discusses the use of progesterone in obstetrics and gynecology. It provides a brief history of progesterone, noting its discovery and isolation in the 1920s. It describes progesterone's natural sources and functions, including roles in the menstrual cycle, pregnancy, and development of female secondary sex characteristics. The document also outlines progesterone's mechanisms of action, pharmacological properties, indications for various obstetric and gynecologic conditions, and potential side effects. It reviews data on progesterone's effectiveness in preventing preterm birth and miscarriage.