The lining of the uterine endometrium thins, or atrophies, when exposed to changing hormonal levels. In particular, reduced exposure to estrogen after menopause or due to medical intervention may cause thinning of the endometrium.

Medications that may cause thinning of the endometrium include progestins and drugs which suppress gonadotropin-releasing hormone, such as leuprolide. Tamoxifen, while pro-estrogenic in the endometrium, can none the less cause a particular form of thinning called "cystic endometrial atrophy."

Thinning of the endometrium is a common cause of post-menopausal abnormal uterine bleeding.