Menstruation

This article is about menstruation in humans. For menstruation in other mammals, see Menstruation (mammal).

Diagram illustrating how the uterus lining builds up and breaks down during the menstrual cycle

Menstruation (also known as a period, among other colloquial terms) is the regular discharge of blood and mucosal tissue from the inner lining of the uterus through the vagina. The menstrual cycle is characterized by the rise and fall of hormones. Menstruation is triggered by falling progesterone levels, and is a sign that pregnancy has not occurred.

The first period, a point in time known as menarche, usually begins between the ages of 12 and 15.[1] Menstruation starting as young as 8 years would still be considered normal.[2] The average age of the first period is generally later in the developing world, and earlier in the developed world.[3] The typical length of time between the first day of one period and the first day of the next is 21 to 45 days in young women. In adults, the range is between 21 and 35 days with the average being 28 days.[2][3] Bleeding usually lasts around 2 to 7 days. Periods stop during pregnancy and typically do not resume during the initial months of breastfeeding.[2] Lochia occurs after childbirth.[4] Menstruation, and with it the possibility of pregnancy, ceases after menopause, which usually occurs between 45 and 55 years of age.[5]

Up to 80% of women do not experience problems sufficient to disrupt daily functioning either during menstruation or in the days leading up to menstruation. Symptoms in advance of menstruation that do interfere with normal life are called premenstrual syndrome (PMS). Some 20 to 30% of women experience PMS, with 3 to 8% experiencing severe symptoms.[6] These include acne, tender breasts, bloating, feeling tired, irritability, and mood changes.[7] Other symptoms some women experience include painful periods (estimates are between 50 and 90%) and heavy bleeding during menstruation and abnormal bleeding at any time during the menstrual cycle.[2] A lack of periods, known as amenorrhea, is when periods do not occur by age 15 or have not re-occurred in 90 days.[2]

  1. ^ Women's Gynecologic Health. Jones & Bartlett Publishers. 2011. p. 94. ISBN 9780763756376. Archived from the original on 26 June 2015.
  2. ^ a b c d e "Menstruation and the menstrual cycle fact sheet". Office of Women's Health. 23 December 2014. Archived from the original on 26 June 2015. Retrieved 25 June 2015.
  3. ^ a b Diaz A, Laufer MR, Breech LL (November 2006). "Menstruation in girls and adolescents: using the menstrual cycle as a vital sign". Pediatrics. 118 (5): 2245–2250. doi:10.1542/peds.2006-2481. PMID 17079600. S2CID 37802775.
  4. ^ "Pregnancy: Physical Changes After Delivery". Cleveland Clinic. Retrieved 16 August 2024.
  5. ^ "Menopause: Overview". National Institutes of Health. 28 June 2013. Archived from the original on 2 April 2015. Retrieved 8 March 2015.
  6. ^ Biggs WS, Demuth RH (October 2011). "Premenstrual syndrome and premenstrual dysphoric disorder". American Family Physician. 84 (8): 918–924. PMID 22010771.
  7. ^ "Premenstrual syndrome (PMS) fact sheet". Office on Women's Health. 23 December 2014. Archived from the original on 28 June 2015. Retrieved 23 June 2015.