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(prōjĕs`tərōn'), female sex hormonehormone,
secretory substance carried from one gland or organ of the body via the bloodstream to more or less specific tissues, where it exerts some influence upon the metabolism of the target tissue.
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 that induces secretory changes in the lining of the uterusuterus,
in most female mammals, hollow muscular organ in which the fetus develops and from which it is delivered at the end of pregnancy. The human uterus is pear-shaped and about 3 in. (7.
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 essential for successful implantation of a fertilized egg. A steroidsteroids,
class of lipids having a particular molecular ring structure called the cyclopentanoperhydro-phenanthrene ring system. Steroids differ from one another in the structure of various side chains and additional rings. Steroids are common in both plants and animals.
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, progesterone is secreted chiefly by the corpus luteum, a group of cells formed in the ovaryovary,
ductless gland of the female in which the ova (female reproductive cells) are produced. In vertebrate animals the ovary also secretes the sex hormones estrogen and progesterone, which control the development of the sexual organs and the secondary sexual characteristics.
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 after the follicle ruptures during the release of the egg cell. If fertilization does not take place, the secretion of progesterone decreases and menstruation occurs. If fertilization does occur, progesterone is secreted during pregnancy by the placenta and acts to prevent spontaneous abortion; the hormone also prepares the mammary glands for milk production. Progesterone is also synthesized from cholesterolcholesterol
, fatty lipid found in the body tissues and blood plasma of vertebrates; it is only sparingly soluble in water, but much more soluble in some organic solvents. A steroid, cholesterol can be found in large concentrations in the brain, spinal cord, and liver.
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 in the cortex of the adrenal glandadrenal gland
or suprarenal gland
, endocrine gland (see endocrine system) about 2 in. (5.1 cm) long situated atop each kidney. The outer yellowish layer (cortex) of the adrenal gland secretes about 30 steroid hormones, the most important of which are aldosterone and
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 where it is a precursor for the synthesis of other steroids including testosteronetestosterone
, principal androgen, or male sex hormone. One of the group of compounds known as anabolic steroids, testosterone is secreted by the testes (see testis) but is also synthesized in small quantities in the ovaries, cortices of the adrenal glands, and placenta, usually
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. Synthetic compounds with progesteronelike activity have been developed that, along with estrogenestrogen
, any one of a group of hormones synthesized by the reproductive organs and adrenal glands in females and, in lesser quantities, in males. The estrogens cause the thickening of the lining of the uterus and vagina in the early phase of the ovulatory, or menstrual, cycle
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, are used in oral contraceptives.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved.


A steroid hormone produced in the corpus luteum and placenta. The hormone has an important physiological role in the luteal phase of the menstrual cycle and in the maintenance of pregnancy. In addition, progesterone produced in the testis and adrenals has a key role as an intermediate in the biosynthesis of androgens, estrogens, and the corticoids (adrenal cortex steroids). See Androgen, Cholesterol, Estrogen, Menstruation, Steroid, Sterol

McGraw-Hill Concise Encyclopedia of Bioscience. © 2002 by The McGraw-Hill Companies, Inc.
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.



in humans and vertebrate animals, a female sex hormone. Chemically, progesterone is a steroid that is synthesized in the body from cholesterol. It is an intermediate in the biosynthesis of all steroid hormones and can form in any tissues that secrete these hormones. Its structural formula is

In humans and higher animals, progesterone is primarily synthesized in the corpus luteum of the ovaries; the luteinizing hormone of the pituitary gland regulates its production. In the blood, progesterone mainly occurs in complexes with proteins.

By interacting with estriadol, another female hormone, progesterone regulates the estrous cycle in mammals and the menstrual cycle in humans. In the preovulatory phase of the sex and reproductive cycles in women, the daily production of progesterone occurs principally in the adrenal cortex and measures 1 to 3 mg. In the postovulatory phase, as much as 20 to 30 mg of progesterone are produced, principally in the corpus luteum. Progesterone produces changes in the uterine mucosa, which prepare the uterus for the implantation of the fertilized egg. When fertilization does not occur, the corpus luteum atrophies and the secretion of progesterone decreases. During a normal pregnancy, the placenta participates in the required daily production of as much as 200 to 250 mg of progesterone. Progesterone suppresses the activity of the smooth musculature of the uterus and thus prevents spontaneous abortion of the fetus; it also inhibits the ovulation of new follicles. The concentration of progesterone in the uterus decreases at the end of pregnancy, which serves as one of the trigger mechanisms of childbirth.

In medicine, progesterone and its synthetic derivatives (generally called progestins, or gestagens) are used to treat various disturbances of pregnancy and the ovarian cycle; they are also used in combination with estrogens as contraceptives. Derivatives of progesterone that act as repellents have been discovered in some insects. Flowering plants have also been found to produce progesterone.

In 1934, A. Butenandt contributed to the discovery of the chemical structure of progesterone.


Savchenko, O. N. Gormony iaichnika i gonadotropnye gormony. Leningrad, 1967.
Heftmann, E. M. Biokhimiia steroidov. Moscow, 1972. (Translated from English.)


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.


C21H30O2 A steroid hormone produced in the corpus luteum, placenta, testes, and adrenals; plays an important physiological role in the luteal phase of the menstrual cycle and in the maintenance of pregnancy; it is an intermediate in the biosynthesis of androgens, estrogens, and the corticoids.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.


a steroid hormone, secreted mainly by the corpus luteum in the ovary, that prepares and maintains the uterus for pregnancy. Formula: C21H30O2
Collins Discovery Encyclopedia, 1st edition © HarperCollins Publishers 2005
References in periodicals archive ?
During the five weeks the women in the study had ultrasound scans, weekly charting of pain and bleeding and weekly tests to check the levels of progesterone and the pregnancy hormone, human chorionic gonadotrophin (hCG).
They showed no trace of the pregnancy hormone HCG (human chorionic gonadotropin).
The altered gene has been found to be involved in both faulty cholesterol regulation and the production of pregnancy hormone, progesterone.
Caused by a pregnancy hormone present in the first trimester, morning sickness can make you tired and queasy - and not just in the morning.
Reserarchers for the study, presented at the European Society for Human Reproduction and Embryology conference in Stockholm this week, found six factors with the greatest impact on miscarriages, levels of progesterone and of the pregnancy hormone human chorionic gonadotropin (hCG), fetus length, the extent of bleeding, and the baby's development.
Your body is reacting to higher levels of the pregnancy hormone HCG and for most women, the first 12 weeks are the worst.
Washington, Apr 21 (ANI): Researchers from Fox Chase Cancer Centre have found that pregnancy hormone hCG protects against breast cancer even in short-term treatments.
The First Response Early Pregnancy Test has ultra-sensitive technology that can detect small amounts of the pregnancy hormone, so you could get the answer first.*
The women were given two pills, one which they took at hospital and the other at home The pills block progesterone,a pregnancy hormone, and cause the lining of the uterus to break down to stop embryos developing.
Pregnancy gingivitis, where the gum margins swell under the influence of the pregnancy hormone, progesterone.
During pregnancy hormone levels in expectant mothers rise as the baby develops in the womb.
Pregnant women are particularly susceptible to it because the pregnancy hormone, progesterone, causes the gum's edge to puff up and soften.