Menstrual Disorders - Causes

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Amenorrhea and Oligomenorrhea

Normal causes of skipped or irregular periods include pregnancy, breast-feeding, hormonal contraception, and perimenopause. Skipped periods are also common during adolescence, when it may take a while before ovulation occurs regularly. Consistently absent periods may be due to the following factors:

• Delayed Puberty. A common cause of primary amenorrhea is delayed puberty due to some genetic factor that delays physical development. Failure of ovarian development is the most common cause of primary amenorrhea.
• Hormonal Changes and Puberty. Oligomenorrhea is a frequent complaint during puberty who are just beginning to have their periods
• Weight Loss and Eating Disorders. Eating disorders are a common cause of amenorrhea in adolescent girls. Extreme weight loss and reduced fat stores lead to hormonal changes that include low thyroid levels (hypothyroidism) and elevated stress hormone levels (hypercortisolism). These changes produce a reduction in reproductive hormones. A syndrome known as the female athlete triad is associated with hormonal changes that occur with the combination of eating disorders, amenorrhea, and osteopenia (loss of bone density that can lead to osteoporosis) in young women who excessively exercise. [For more information, see In-Depth Report #49: Eating Disorders.]
• Polycystic Ovarian Syndrome (PCOS). PCOS is a condition in which the ovaries produce high amounts of androgens (male hormones), particularly testosterone. PCOS occurs in about 10% of women of childbearing age, and amenorrhea or oligomenorrhea (infrequent menses) is quite common.
• Elevated Prolactin Levels (Hyperprolactinemia). Prolactin is a hormone produced in the pituitary gland that stimulates breast development and milk production in association with pregnancy. High levels of prolactin (hyperprolactinemia) in women who are not pregnant or nursing can reduce gonadotropin hormones and inhibit ovulation, thus causing amenorrhea.
• Premature Ovarian Failure (POF). POF is the early depletion of follicles before age 40. In most cases, it leads to premature menopause. POF is a significant cause of infertility.
• Structural Problems. In some cases, structural problems or scarring in the uterus may prevent menstrual flow. Inborn genital tract abnormalities may also cause primary amenorrhea.
• Stress. Physical and emotional stress may block the release of luteinizing hormone, causing temporary amenorrhea.
• Athletic Training. Amenorrhea or oligomenorrhea associated with vigorous activity is related to stress and not weight loss. Female athletes who use anabolic steroids will often have amenorrhea or oligomenorrhea.

• Other Medical Conditions. Epilepsy, thyroid problems, celiac sprue, metabolic syndrome, and Cushing's disease are associated with amenorrhea.

Review Date: 07/26/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

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