Premature ovarian failure (POF) is also referred to as premature menopause or primary ovarian insufficiency, and it is characterized by the inability to ovulate and an early loss of function of the ovaries altogether due to a lack of or no follicles in the ovary in women who are under the age of 40 (prior to the typical onset of menopause). POF leads to subfertility or infertility and is also linked to osteoporosis and other autoimmune disorders. It can be a result of genetic abnormalities, removal of the ovaries, or prior radiation therapy or chemotherapy. Premature ovarian failure differs from menopause in that women with premature ovarian failure may have occasional or irregular periods and may possibly become pregnant.