Primary ovarian insufficiency (POI), also known as premature ovarian failure, happens when a woman’s ovaries stop working normally before she is 40.
Many women naturally experience reduced fertility when they are about 40 years old. They may start getting irregular menstrual periods as they transition to menopause. For women with POI, irregular periods and reduced fertility start before the age of 40. Sometimes it can start as early as the teenage years.
POI is different from premature menopause. With premature menopause, your periods stop before age 40. You can no longer get pregnant. The cause can be natural or it can be a disease, surgery, chemotherapy, or radiation. With POI, some women still have occasional periods. They may even get pregnant. In most cases of POI, the cause is unknown.