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menstruationThere 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 CycleIn 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 SyndromeMany 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.
BibliographySee 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. Copyright © 2001-09 Columbia University Press. All rights reserved.
- amenorrhea
Amenorrhea, cessation of menstruation. Primary amenorrhea is a delay in or a failure to start menstruation; secondary amenorrhea is an unexpected stop to the menstrual cycle. It is caused by d...
- premenstrual syndrome
Premenstrual syndrome (PMS), any of various symptoms experienced by women of childbearing age in the days immediately preceding menstruation. It is most common in women in their twenties and t...
- ketoprofen
Ketoprofen, nonsteroidal anti-inflammatory drug (NSAID) with anti-inflammatory, analgesic, and fever-reducing effects, used to relieve the symptoms of headaches, arthritis, and painful menstru...
- naproxen
Naproxen and naproxen sodium, potent nonsteroidal anti-inflammatory drugs (NSAID) used to alleviate the minor pain of arthritis, menstruation, headaches, and the like, and to reduce fever. Alo...
- menopause
Menopause or climacteric, transitional phase in a woman's life when the ovaries stop releasing eggs, ovarian production of estrogen and other hormones tapers off, and menstruation ceases. It r...
- endometriosis
Endometriosis, a condition in which small pieces of the endometrium (the lining of the uterus) migrate to other places in the pelvic area. The endometrial fragments may move to the fallopian t...
- toxic shock syndrome
Toxic shock syndrome (TSS). acute, sometimes fatal, disease characterized by high fever, nausea, diarrhea, lethargy, blotchy rash, and sudden drop in blood pressure. It is caused by Staphyloco...
- ibuprofen
Ibuprofen, nonsteroidal anti-inflammatory drug (NSAID) that reduces pain, fever, and inflammation. Along with naproxen and ketoprofen, ibuprofen belongs to the propionic acid class of NSAIDs. ...
- puberty
Puberty, period during which the onset of sexual maturity occurs. It usually takes place between the ages of 10 and 15 in both sexes but sometimes occurs as early as 7 or 8 years of age in fem...
- progesterone
Progesterone, female sex hormone that induces secretory changes in the lining of the uterus essential for successful implantation of a fertilized egg. A steroid, progesterone is secreted chief...
