Primary ovarian insufficiency (previously known as premature ovarian failure) is a medical condition that affects some women before age 40. It causes their ovaries to stop functioning properly before the women reach menopause.
When this occurs, your ovaries are unable to manufacture specific amounts of the hormone estrogen; nor release eggs regularly. This condition often leads to infertility.
Normally a healthy woman’s ovaries would produce estrogen. Estrogen is the hormone that controls your menstrual cycle and causes you to become fertile/pregnant.
In the case of primary ovarian insufficiency, the ovaries stop functioning long before menopause sets in. (Average age of menopause is 51.) If you are less than 40 years of age; and your ovaries have stopped producing eggs. Plus your menstrual cycle has ceased then you should quickly book an appointment with your doctor to receive the best approach to treatment.
Primary ovarian insufficiency could sometimes be confused with premature menopause. But these 2 conditions are very much different. They aren't the same.
According to Mayo Clinic, " Women with primary ovarian insufficiency can have irregular or occasional periods for years and might even get pregnant. But women with premature menopause stop having periods and can't become pregnant." 
Hence, restoring the estrogen levels in women with primary ovarian insufficiency has helped prevent some further complications such as osteoporosis which occurs as a result of low estrogen.
Symptoms of POI
Irregular or skipped periods (this could be present for years; or it could develop after a pregnancy; or after quitting birth contraceptives)
Irritability or difficulty concentrating
Difficulty getting pregnant
Decreased physical intimacy
Complications of POI
Infertility. Inability to get pregnant could be a complication. Though in rare cases, pregnancy occurs until the eggs deplete.
Osteoporosis. Estrogen helps strengthen strong bones. However women with decreased levels have high risk of developing osteoporosis.
Depression or anxiety. The risk of infertility and complications arising from low estrogen levels have caused depression/anxiety in some women.
 Primary ovarian insufficiency. Merck Manual Professional Version. https://www.merckmanuals.com/professional/gynecology-and-obstetrics/menstrual-abnormalities/primary-ovarian-insufficiency. Accessed July 23, 2019.
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