How is pregnenolone converted into progesterone?

Pregnenolone is converted into progesterone through an enzymatic process that occurs within the endoplasmic reticulum of the cell.1

After pregnenolone is synthesized from cholesterol in the mitochondria, it is transported out into the endoplasmic reticulum. There, it undergoes further enzymatic conversion to become progesterone. Chemically, this transformation is characterized as a dehydrogenation process. Once formed, progesterone serves as a vital precursor that is subsequently converted into other specific steroid hormones, such as androgens, estrogens, mineralocorticoids, and glucocorticoids.12