Functions of progesterone are many, for instance:

• Precursor of oestrogen and testosterone
• Maintain secretory endometrium
• Protects against breast fibrocysts
• Natural diuretic
• Natural anti-depressant
• Helps maintain thyroid hormone action
• Protects against endometrial and breast cancer
• Precursor of cortisone synthesis by adrenal cortex

Progesterone can also be converted to other important hormones, which are essential for blood pressure, stress response and sugar and electrolyte balance.

Natural progesterone may promote new bone formation.