Estrogen

Estrogen is the primary female sex hormone, produced mainly by the ovaries (with smaller amounts from body fat and the adrenal glands), responsible for regulating the menstrual cycle, supporting bone health, and maintaining reproductive tissue. In PCOS, estrogen levels may be normal or even slightly elevated due to continuous production from multiple immature follicles and conversion of androgens to estrogen in fat tissue, yet this estrogen fails to support normal ovulation because of the overpowering effects of excess androgens and disrupted LH/FSH ratios. The resulting imbalance between estrogen and progesterone—with progesterone being low or absent due to anovulation—can lead to endometrial thickening and increased risk of endometrial hyperplasia.