menstruation, periodic flow of blood and cells from the lining of the uterus in humans and most other primates, occurring about every 28 days in women. Menstruation commences at puberty (usually between age 10 and 17). The onset of menstruation, called menarche, signals the body's coming readiness for childbearing. It continues, unless interrupted by pregnancy until menopause (around age 50).

There have been many myths and taboos associated with menstruation. Some cultures isolated women or thought the menstrual flow "unclean" or a "curse." More recent taboos against exercise or sexual intercourse during menstruation are slowly lifting. Some scientists have asked why menstruation occurs at all—why the uterine lining does not remain in place, regenerating itself as other parts of the body (such as the skin and digestive tract) do. One theory is that menstruation is a defense against microbes that enter the uterus with incoming sperm.

The Menstrual Cycle

In the first phase of each cycle, the lining, or endometrium, of the uterus undergoes rapid proliferation of cells and venous channels in preparation for pregnancy. Midway through the cycle an ovum (egg) is released from an ovary. If, while passing through the fallopian tube the ovum is fertilized by a sperm, implantation in the uterus occurs and the thickened lining helps support the pregnancy. When the ovum is not fertilized, this tissue and blood are shed. The proliferation of the uterine wall then begins once more in expectation of the next release of an ovum, and if conception does not take place, it sloughs off again. The process continues monthly until pregnancy occurs or until ovulation ceases at menopause.

The natural rhythm of the menstrual cycle may be broken or temporarily halted by hormonal imbalance, malnutrition, illness, or emotional disturbance (see amenorrhea). Menstruation is controlled by the hypothalamus and the pituitary gland and hormones, such as estrogen, which prepares the lining of the uterus, and progesterone, which helps maintain a pregnancy.

Dysmenorrhea and Premenstrual Syndrome

Many women experience painful menstruation, or dysmenorrhea. The uterine contractions that result in the cramps experienced by these women appear to be caused by hormones called prostaglandins that are produced in the second half of the cycle. Oral contraceptives and other drugs that reduce the production of prostaglandins are sometimes used in treatment. Other women experience symptoms such as behavioral changes, breast tenderness, and fatigue during the week immediately preceding menstruation, a condition referred to as premenstrual syndrome, or PMS.


See publications of the National Institute of Child Health and Human Development; Boston Women's Health Book Collective, Our Bodies, Ourselves for the New Century (1998).

The Columbia Encyclopedia, 6th ed. Copyright© 2018, The Columbia University Press.

Menarche: Selected full-text books and articles

Handbook of Psychology and Health By Andrew F. Baum; Jerome E. Singer Lawrence Erlbaum Associates, vol.2, 1982
Librarian's tip: Chap. 6 "Developmental Processes in the Experience of Menarche"
Development during the Transition to Adolescence By Megan R. Gunnar; W. Andrew Collins Lawrence Erlbaum Associates, 1988
Librarian's tip: Chap. 3 "Adapting to Menarche: Familial Control and Conflict"
Toward a New Understanding of Early Menarche: The Role of Environmental Stress in Pubertal Timing By Wierson, Michelle; Long, Patricia J.; Forehand, Rex L Adolescence, Vol. 28, No. 112, Winter 1993
Paradoxical Constructions of Self: Educating Young Women about Menstruation By Charlesworth, Dacia Women and Language, Vol. 24, No. 2, Fall 2001
Peer-reviewed publications on Questia are publications containing articles which were subject to evaluation for accuracy and substance by professional peers of the article's author(s).
Biological-Psychosocial Interactions in Early Adolescence By Richard M. Lerner; Terryl T. Foch Lawrence Erlbaum Associates, 1987
Librarian's tip: Chap. 6 "Pubertal Processes and Girls' Psychological Adaptation"
Adolescence: Biological and Psychosocial Perspectives By Benjamin B. Wolman Greenwood Press, 1998
Librarian's tip: "Puberty in Females" begins on p. 10
The Natural History of Population By Raymond Pearl Oxford University Press, 1939
Librarian's tip: "Menarche, Menopause, and Reproductive Span" begins on p. 46
Menstrual Disorders By Annette Scambler; Graham Scambler Tavistock Routledge, 1993
Librarian's tip: "Menarche and the Menstrual Cycle" begins on p. 1
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