a- Pregnanediol is a naturally occurring chemical compound that is derived from the hormone progesterone. It is a metabolite of progesterone, meaning that it is produced when the body breaks down and processes progesterone. A-Pregnanediol can be found in the urine and is often measured in medical tests to assess progesterone levels, particularly during pregnancy. Monitoring the levels of a-Pregnanediol can provide important information about the functioning of the corpus luteum (a temporary endocrine structure in the ovaries) and can be used to confirm pregnancy or track the menstrual cycle.