Primary ovarian insufficiency (POI), also known as premature ovarian failure, describes a pathologic condition that occurs when the hypothalamic-pituitary-gonadal axis stops functioning earlier than it should. Historically, the cut-off age between having these changes associated with perimenopause / menopause versus having them associated with POI has been 40 years.

The pathophysiology of POI is related to decreasing follicles (low starting amount versus increased destruction) and/or poor follicular response to gonadotrophins. The etiology for POI is unknown in the majority of cases but may be related to injury to ovarian tissue caused by surgery, chemotherapy, radiation, or autoimmune processes. Rarely, autoimmune oophoritis, which may occur with adrenal autoimmunity, can be a cause. There is evidence of a genetic component to this condition; underlying fragile X syndrome or Turner syndrome can also cause POI.

Patients can present with a variety of complaints, but the most common presentation is absence or decreased frequency of menses. Other symptoms may include vasomotor symptoms, mood changes, vaginal dryness, recurrent miscarriage, or inability to become pregnant.