Breast atrophy is the normal or spontaneous atrophy or shrinkage of the breasts.

[1] Breast atrophy commonly occurs in women during menopause when estrogen levels decrease.

[2][3][4] It can also be caused by hypoestrogenism and/or hyperandrogenism in women in general,[1] such as in antiestrogen treatment for breast cancer, in polycystic ovary syndrome (PCOS),[5][6] and in malnutrition such as that associated with eating disorders like anorexia nervosa or with chronic disease.

[8][9] In the treatment of gynecomastia in males and macromastia in women, and in hormone replacement therapy (HRT) for trans men,[10] breast atrophy may be a desired effect.

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