Amenorrhea is the absence of menstruation, meaning one or more missed menstrual periods. The Mayo Clinic defines it as when women have missed at least three periods in a row or when girls haven't begun menstruation by the age of 16.
According to the University of Maryland Medical Center (UMMC), there are two types of amenorrhea: primary and secondary. When a girl reaches age 16 and has not had a period, she may have primary amenorrhea.
When a woman who has been having periods misses three in a row, she is considered to have secondary amenorrhea. Secondary amenorrhea is more common than primary amenorrhea.
The most common cause of amenorrhea is pregnancy. Other causes include problems with the reproductive organs or with the glands that help regulate hormone levels.
The National Institutes of Health (NIH) say being born with poorly formed genital or pelvic organs (missing uterus or vagina, vaginal septum, cervical stenosis, or imperforate hymen) can lead to primary amenorrhea.
UMMC goes on to say secondary amenorrhea can be caused by pregnancy or breast-feeding, some types of birth control, certain types of medication (such as corticosteroids) or hormone imbalance. It may also be caused by low body weight, too much exercise, thyroid problems, pituitary tumor, stress, and premature menopause.
The Mayo Clinic reports there are factors that may increase the risk of amenorrhea. These include family history, eating disorders and athletic training.
The absence of menstruation is one symptom of amenorrhea. UMMC says symptoms of primary amenorrhea may include headaches, abnormal blood pressure, vision problems, acne and excessive hair growth. And symptoms of secondary amenorrhea may include nausea, swollen breasts, headaches, vision problems, being very thirsty, an enlarged thyroid gland and darkening skin.
Treatments for amenorrhea include hormone therapy, medication and surgery.
eMedicineHealth says hormone replacement therapy, consisting of an estrogen and a progestin, can be a treatment for women with estrogen deficiency because ovarian function cannot be restored.