Progesterone. It is a steroid hormone responsible for the decidualization of the endometrium and for maintaining.
Corpus luteum is necessary for establishing and maintaining pregnancy in females. It is a yellow hormone-secreting body found in the female reproductive system that is formed in the ovary at the site of the sac which has released after maturing the egg through the process of ovulation. Corpus luteum is made of lutein cells which develop immediately after ovulation after the lipids and yellow pigments accumulate within the granulosa cells that line the follicle.
Corpus luteum secretes progesterone and estrogen. They are critical in causing changes in the uterus making it more suitable for embryo-implantation in case of fertilization and otherwise, it becomes inactive after around 14 days causing menstruation.