in taxon has primary output progesterone C21-steroid hormone biosynthetic process progesterone biosynthetic process progesterone biosynthesis The chemical reactions and pathways resulting in the formation of progesterone, a steroid hormone produced in the ovary which prepares and maintains the uterus for pregnancy. Also found in plants. progesterone formation progesterone anabolism GO:0006701 progesterone synthesis biosynthetic process ketone biosynthetic process progesterone metabolic process olefinic compound biosynthetic process