What causes menstrual irregularities?

Menstrual irregularities can have a variety of causes, including pregnancy, hormonal imbalances, infections, diseases, trauma, and certain medications.1,2,3,4,5,6

Causes of irregular periods (generally light) include:2

  • What causes your period to be irregular?Perimenopause (generally in the late 40s and early 50s)
  • Primary ovarian insufficiency (POI)
  • Eating disorders (anorexia nervosa or bulimia)
  • Excessive exercise
  • Thyroid dysfunction (too much or too little thyroid hormone)
  • Elevated levels of the hormone prolactin, which is made by the pituitary gland to help the body produce milk
  • Uncontrolled diabetes 
  • Cushing's syndrome (elevated levels of the hormone cortisol, used in the body's response to stress)
  • Late-onset congenital adrenal hyperplasia (problem with the adrenal gland)
  • Hormonal birth control (birth control pills, injections, or implants)
  • Hormone-containing intrauterine devices (IUDs)
  • Scarring within the uterine cavity (Asherman's syndrome)
  • Medications, such as those to treat epilepsy or mental health problems

Common causes of heavy or prolonged menstrual bleeding include:2,7

  • Adolescence (during which cycles may not be associated with ovulation)
  • Polycystic ovary syndrome (PCOS) (bleeding irregular but heavy)
  • Uterine fibroids (benign growths of uterine muscle)
  • Endometrial polyps (benign overgrowth of the lining of the uterus)
  • Adenomyosis (the presence of uterine lining in the wall of the uterus)
  • Nonhormonal IUDs
  • Bleeding disorders, such as leukemia, platelet disorders, clotting factor deficiencies, or (less common) von Willebrand disease
  • Pregnancy complications (miscarriage)

Common causes of dysmenorrhea (menstrual pain) include:6,9


  1. American College of Obstetricians and Gynecologists (ACOG). (2012). FAQ: Abnormal uterine bleeding. Retrieved on May 24, 2016, from http://www.acog.org/Patients/FAQs/Abnormal-Uterine-Bleeding external link (PDF 464 KB)
  2. Sweet, M. G., Schmidt-Dalton, T. A., Weiss, P. M., & Madsen, K. P. (2012). Evaluation and management of abnormal uterine bleeding in premenopausal women. American Family Physician, 85, 35–43.
  3. Master-Hunter, T., & Heiman, D. L. (2006). Amenorrhea: Evaluation and treatment. American Family Physician, 73, 1374–1382.
  4. Apgar, B. S., Kaufman, A. H., George-Nwogu, U., & Kittendorf, A. (2007). Treatment of menorrhagia. American Family Physician, 75, 1813–1819.
  5. Practice Committee of the American Society for Reproductive Medicine. (2008). Current evaluation of amenorrhea [Review]. Fertility and Sterility, 90, S219–S225.
  6. French, L. (2005). Dysmenorrhea. American Family Physician, 71, 285–291.
  7. Godfrey, E. M., Folger, S. G., Jeng, G., Jamieson, D. J., & Curtis, K. M. (2013). Treatment of bleeding irregularities in women with copper-containing IUDs: A systematic review. Contraception, 87(5), 549–566. Retrieved August 2, 2016, from http://www.contraceptionjournal.org/article/S0010-7824(12)00816-5/abstract external link
  8. Centers for Disease Control and Prevention. (2016). Chlamydia—CDC fact sheet. Retrieved on August 2, 2016, from http://www.cdc.gov/std/chlamydia/stdfact-chlamydia.htm
  9. American College of Obstetricians and Gynecologists. (2016). FAQ: Gonorrhea, chlamydia, and syphilis. Retrieved on August 2, 2016, from http://www.acog.org/Patients/FAQs/Gonorrhea-Chlamydia-and-Syphilis external link
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