In the female reproductive system, the menstrual cycle is a recurring cycle of physiologic changes that occurs in reproductive-age females. Physiology (from Greek grc φύσις physis, "nature origin" and grc -λογία -logia) is the study of the mechanical physical Female (♀ is the Sex of an Organism, or a part of an organism which produces ova (egg cells Overt menstruation (where there is blood-flow from the vagina) occurs primarily in humans and close evolutionary relatives such as chimpanzees. The vagina (from Latin, literally " Sheath " or " Scabbard " is a fibromuscular tubular tract leading from the Uterus Chimpanzee (often shortened to chimp) is the common name for the two extant Species of Apes in the Genus Pan. ^[1] The females of other species of placental mammal have estrous cycles, in which the endometrium is completely reabsorbed by the animal (covert menstruation) at the end of its reproductive cycle. See also Evolution of mammals Eutheria ("true beast" are a group of Mammals consisting of Placental mammals plus all extinct Mammals Oestrus is also the biological genus name of the gadfly. The estrous cycle (also oestrous cycle; derived from Latin This article concentrates on the menstrual cycle as it occurs in human beings.

The menstrual cycle is under the control of the hormone system and is necessary for reproduction. Hormones (from Greek ὁρμή - "impetus" are chemicals released by cells that affect cells in other parts of the body Reproduction is the Biological process by which new individual Organisms are produced Menstrual cycles are counted from the first day of menstrual flow, because the onset of menstruation corresponds closely with the hormonal cycle. The menstrual cycle may be divided into several phases, and the length of each phase varies from woman to woman and cycle to cycle. Average values are shown below:

Name of phase	Days
menstrual phase	1–4
follicular phase (also known as proliferative phase)	5–13
ovulation (not a phase, but an event dividing phases)	14
luteal phase (also known as secretory phase)	15–26
ischemic phase (some sources group this with secretory phase)	27–28

During the follicular phase the lining of the uterus thickens, stimulated by gradually increasing amounts of estrogen. The endometrium is the inner membrane of the Mammalian Uterus. The uterus (from the Latin word for womb) is the major Female reproductive organ of most Mammals including Humans One end the Estrogens (US otherwise oestrogens or œstrogens) are a group of Steroid compounds named for their importance in the Estrous cycle, Follicles in the ovary begin developing under the influence of a complex interplay of hormones, and after several days one or occasionally two follicles become dominant (non-dominant follicles atrophy and die). "Ovaria" redirects here This is also a proposed section and a Synonym of Solanum. The dominant follicle releases an ovum or egg in an event called ovulation. An ovum (plural ova) is a Haploid Female reproductive cell or Gamete. Note This article deals primarily with Human ovulation nonhuman Animal ovulation is touched on briefly at the conclusion (An egg that is fertilized by a spermatozoon will become a zygote, taking one to two weeks to travel down the fallopian tubes to the uterus. A spermatozoon or spermatozoan ( pl spermatozoa) from the Ancient Greek σπέρμα (seed and ζῷον (living being and more commonly known For soil improvement see Fertilization (soil. The Fallopian tubes, also known as oviducts, uterine tubes, and salpinges ( singular salpinx) are two very fine tubes lined with ciliated If the egg is not fertilized within about a day of ovulation, it will die and be absorbed by the woman's body. ^[2]) After ovulation the remains of the dominant follicle in the ovary become a corpus luteum; this body has a primary function of producing large amounts of progesterone. The corpus luteum ( Latin for "yellow body" (plural corpora lutea) is a temporary Endocrine structure in mammals involved in production of Progesterone is a C-21 Steroid Hormone involved in the Female Menstrual cycle, Pregnancy (supports Gestation Under the influence of progesterone, the endometrium (uterine lining) changes to prepare for potential implantation of an embryo to establish a pregnancy. Implantation is an event that occurs early in pregnancy in which the Embryo adheres to the wall of Uterus. Pregnancy ( Latin graviditas) is the carrying of one or more offspring known as a Fetus or Embryo, inside the Uterus of a Female If implantation does not occur within approximately two weeks, the corpus luteum will die, causing sharp drops in levels of both progesterone and estrogen. These hormone drops cause the uterus to shed its lining in a process termed menstruation.

Contents 1 Terminology 2 Phases of the menstrual cycle 2.1 Menstruation 2.2 Follicular phase 2.3 Ovulation 2.4 Luteal phase 3 The fertile window 4 Hormonal control 4.1 Gonadal 4.2 Hypothalamus and pituitary 4.3 Cyclic effects upon nervous system 5 Hidden ovulation 6 The ovary as an egg-bank 7 Cycle abnormalities 7.1 Anovulation 7.2 Flow 7.3 Cycle length 7.4 Early menarche 8 Contraception and menstruation 8.1 Hormonal options 8.2 Effects on menstruation 8.3 Control and flexibility 8.4 Other contraceptive methods 9 Menstruation and the moon 10 Menstrual cycles in other mammals 11 References 12 Notes 13 External links

Terminology

A woman's first menstruation is termed menarche, and is one of the later stages of puberty in girls. Menarche (American English məˈnɑrki British English mɛˈnɑːki is the first menstrual period, or first menstrual bleeding in the females of Human beings The average age of menarche in humans is 12 years, but is normal anywhere between ages 8 and 16. Factors such as heredity, diet and overall health can accelerate or delay menarche. ^[3] The cessation of menstrual cycles at the end of a woman's reproductive life is termed menopause. Menopause is the permanent shutting down of the female Reproductive system, a considerable length of time before the end of the lifespan The average age of menopause in women is 51 years, with anywhere between 40 and 58 being common. Menopause before age 35 is considered premature. The age of menopause is largely a result of genetics; however, illnesses, certain surgeries, or medical treatments may cause menopause to occur earlier. ^[4]

The length of a woman's menstrual cycle will typically vary, with some shorter cycles and some longer cycles. A woman who experiences variations of less than eight days between her longest cycles and shortest cycles is considered to have regular menstrual cycles. It is unusual for a woman to experience cycle length variations of less than four days. Length variation between eight and 20 days is considered moderately irregular. Variation of 21 days or more between a woman's shortest and longest cycle lengths is considered very irregular (see cycle abnormalities). ^[5]

It is important to do a breast exam during the same time of the cycle as opposed to the same time of the month given that most women do not have cycles that correspond exactly with the calender month and the breast architecture fluctuates considerable given the phase of the menstrual cycle.

Phases of the menstrual cycle

Menstruation

Main article: Menstruation

Menstruation is also called menstrual bleeding, menses, a period or catamenia. See also "Mensuration" a term sometimes used to describe Measurement, particularly in the context of Forestry. The flow of menses normally serves as a sign that a woman has not become pregnant. Pregnancy ( Latin graviditas) is the carrying of one or more offspring known as a Fetus or Embryo, inside the Uterus of a Female (However, this cannot be taken as certainty, as sometimes there is some flow of blood in early pregnancy. ) During the reproductive years, failure to menstruate may provide the first indication to a woman that she may have become pregnant.

Eumenorrhea denotes normal, regular menstruation that lasts for a few days (usually 3 to 5 days, but anywhere from 2 to 7 days is considered normal). ^[6] The average blood loss during menstruation is 35 millilitres with 10–80 ml considered normal;^[7] many women also notice shedding of the endometrium lining that appears as tissue mixed with the blood. The endometrium is the inner membrane of the Mammalian Uterus. An enzyme called plasmin — contained in the endometrium — tends to inhibit the blood from clotting. Enzymes are Biomolecules that catalyze ( ie increase the rates of Chemical reactions Almost all enzymes are Proteins Plasmin is an important Enzyme ( present in Blood that degrades many Blood plasma proteins most notable Fibrin clots The degradation Coagulation is a complex process by which Blood forms Clots It is an important part of Hemostasis (the cessation of blood loss from a damaged vessel whereby Because of this blood loss, women have higher dietary requirements for iron than do males to prevent iron deficiency. Iron (ˈаɪɚn is a Chemical element with the symbol Fe (ferrum and Atomic number 26 For a more specific and detailed discussion of Anemia caused by iron deficiency see the Wikipedia article Iron deficiency anemia. Many women experience uterine cramps during this time (severe cramps or other symptoms are called dysmenorrhea), as well as other premenstrual syndrome symptoms. The uterus (from the Latin word for womb) is the major Female reproductive organ of most Mammals including Humans One end the Dysmenorrhea (or dysmenorrhoea) is a medical condition characterized by severe Uterine Pain during Menstruation. Premenstrual syndrome ( PMS) (sometimes referred to as PMT or Premenstrual Tension) is a collection of physical psychological and emotional symptoms A vast industry of sanitary products has grown to help women during their menstruation. See also "Mensuration" a term sometimes used to describe Measurement, particularly in the context of Forestry.

Follicular phase

Main article: Follicular phase

Through the influence of a rise in follicle stimulating hormone (FSH), five to seven tertiary-stage ovarian follicles are recruited for entry into the next menstrual cycle. The follicular phase (or proliferative phase) is the phase of the Estrous cycle, (or in humans and Great apes the Menstrual cycle) during Follicle-stimulating hormone ( FSH) is a Hormone synthesized and secreted by Gonadotropes in the Anterior pituitary gland. Ovarian follicle is the basic unit of female reproductive biology and is composed of a roughly spherical aggregations of cells found in the Ovary. These follicles, that have been growing for the better part of a year in a process known as folliculogenesis, compete with each other for dominance. In Biology, folliculogenesis is the maturation of the Ovarian follicle, a densely-packed shell of Somatic cells that contains an immature Oocyte Under the influence of several hormones, all but one of these follicles will undergo atresia, while one (or occasionally two) dominant follicles will continue to maturity. As they mature, the follicles secrete increasing amounts of estradiol, an estrogen. Estradiol (17β-estradiol (also oestradiol) is a Sex hormone. Estrogens (US otherwise oestrogens or œstrogens) are a group of Steroid compounds named for their importance in the Estrous cycle,

The estrogens that follicles secrete initiate the formation of a new layer of endometrium in the uterus, histologically identified as the proliferative endometrium. Estrogens (US otherwise oestrogens or œstrogens) are a group of Steroid compounds named for their importance in the Estrous cycle, The endometrium is the inner membrane of the Mammalian Uterus. The estrogen also stimulates crypts in the cervix to produce fertile cervical mucus, which may be noticed by women practicing fertility awareness. Crypts are anatomical structures that are narrow but deep invaginations into a larger structure The cervix (from Latin "neck" is the lower narrow portion of the Uterus where it joins with the top end of the Vagina. Fertility awareness (FA refers to a set of practices used to determine the fertile and infertile phases of a woman's Menstrual cycle.

Ovulation

Main article: Ovulation

When the egg has matured, it secretes enough estradiol to trigger the acute release of luteinizing hormone (LH). Luteinizing hormone ( LH, also known as lutropin) is a Hormone produced by the Anterior pituitary gland. In the average cycle this LH surge starts around cycle day 12 and may last 48 hours. The release of LH matures the egg and weakens the wall of the follicle in the ovary. This process leads to ovulation: the release of the now mature ovum, the largest cell of the body (with a diameter of about 0. Note This article deals primarily with Human ovulation nonhuman Animal ovulation is touched on briefly at the conclusion An ovum (plural ova) is a Haploid Female reproductive cell or Gamete. 5 mm). Which of the two ovaries — left or right — ovulates appears essentially random; no known left/right co-ordination exists. The egg is swept into the fallopian tube by the fimbria - a fringe of tissue at the end of each fallopian tube. The Fallopian tubes, also known as oviducts, uterine tubes, and salpinges ( singular salpinx) are two very fine tubes lined with ciliated In the female reproductive system the fimbria (plural fimbriae) is a fringe of tissue around the ostium of the Fallopian tube, in the direction of the Ovary If fertilization occurs, it will happen in the fallopian tube.

In some women, ovulation features a characteristic pain called mittelschmerz (German term meaning 'middle pain') which may last a few hours. Mittelschmerz ( German: "middle pain" is a medical term for "ovulation pain" or "midcycle pain" The sudden change in hormones at the time of ovulation also causes light mid-cycle blood flow from the vagina of some women. An unfertilized egg will eventually disintegrate or dissolve.

Luteal phase

Main article: Luteal phase

The corpus luteum is the solid body formedsadfas in the ovaries after the egg has been released into the fallopian tube which continues to grow and divide for a while. The luteal phase (or secretory phase) is the latter phase of the Menstrual cycle (in humans and a few other animals or the Estrous cycle (in other After ovulation, the residual follicle transforms into the corpus luteum under the support of the pituitary hormones. The corpus luteum ( Latin for "yellow body" (plural corpora lutea) is a temporary Endocrine structure in mammals involved in production of This corpus luteum will produce progesterone in addition to estrogens for approximately the next 2 weeks. Progesterone is a C-21 Steroid Hormone involved in the Female Menstrual cycle, Pregnancy (supports Gestation Progesterone plays a vital role in converting the proliferative endometrium into a secretory lining receptive for implantation and supportive of the early pregnancy. Implantation is an event that occurs early in pregnancy in which the Embryo adheres to the wall of Uterus. Pregnancy ( Latin graviditas) is the carrying of one or more offspring known as a Fetus or Embryo, inside the Uterus of a Female It raises the body temperature by 0. 25 °C to 0. 5 °C (0. 5 °F to 1. 0 °F), thus women who record their basal body temperature on a daily basis will notice that they have entered the luteal phase. Basal body temperature is the body temperature measured immediately after awakening and before any physical activity has been undertaken If fertilization of an egg has occurred, it will travel as an early blastocyst through the fallopian tube to the uterine cavity and implant itself 6 to 12 days after ovulation. The blastocyst is the structure formed in early Embryogenesis, after the formation of the Blastocoel, but before Implantation. Shortly after implantation, the growing embryo will signal its existence to the maternal system. One very early signal consists of human chorionic gonadotropin (hCG), a hormone that pregnancy tests can measure. Human chorionic gonadotropin ( hCG) is a Glycoprotein Hormone produced in Pregnancy that is made by the Embryo soon after conception A pregnancy test attempts to determine whether or not a female is pregnant. This signal has an important role in maintaining the corpus luteum and enabling it to continue to produce progesterone. In the absence of a pregnancy and without hCG, the corpus luteum demises and inhibin and progesterone levels fall. Inhibin is a peptide that is an inhibitor of FSH Synthesis and Secretion, and participates in the regulation of the Menstrual cycle This will set the stage for the next cycle. Progesterone withdrawal leads to menstrual shedding (progesterone withdrawal bleeding), and falling inhibin levels allow FSH levels to rise to raise a new crop of follicles. Progestagens (also spelled progestogens or gestagens) are Hormones that produce effects similar to those of Progesterone, the only natural progestagen

The fertile window

The length of the follicular phase — and consequently the length of the menstrual cycle — may vary widely. The luteal phase, however, almost always takes the same number of days for each woman: Some women have a luteal phase of 10 days, others 16 days, while the average is 14 days. Normal sperm life inside a woman ranges from 1-5 days, though a pregnancy resulting from sperm life of 8 days has been documented. A spermatozoon or spermatozoan ( pl spermatozoa) from the Ancient Greek σπέρμα (seed and ζῷον (living being and more commonly known ^[8][9][10] The most fertile period (the time with the highest likelihood of pregnancy resulting from sexual intercourse) covers the time from some 5 days before ovulation until 1–2 days after ovulation. Sexual intercourse, in its biological sense is the act in which the male reproductive organ (in humans and other higher animals enters the female reproductive tract In an average 28 day cycle with a 14-day luteal phase, this corresponds to the second and the beginning of the third week of the cycle. Fertility awareness methods of birth control attempt to determine the precise time of ovulation in order to find the relatively fertile and the relatively infertile days in the cycle. Fertility awareness (FA refers to a set of practices used to determine the fertile and infertile phases of a woman's Menstrual cycle. Birth control, sometimes synonymous with contraception, is a regimen of one or more actions devices or Medications followed in order to deliberately prevent

People who have heard about the menstrual cycle and ovulation often mistakenly assume, for contraceptive purposes, that menstrual cycles regularly take 28 days, and that ovulation always occurs 14 days after beginning of the menses. Birth control, sometimes synonymous with contraception, is a regimen of one or more actions devices or Medications followed in order to deliberately prevent This assumption may lead to unintended pregnancies. Note too that not every event of blood flow counts as a menstruation, and this can mislead people in their calculation of the fertile window.

If a woman wants to conceive, the most fertile time occurs between 19 and 10 days prior to the expected menses. Many women use ovulation detection kits that detect the presence of the LH surge in the urine to indicate the most fertile time. Other ovulation detection systems rely on observation of one or more of the three primary fertility signs (basal body temperature, cervical fluid, and cervical position). Basal body temperature is the body temperature measured immediately after awakening and before any physical activity has been undertaken

Among women living closely together, the onsets of menstruation may tend to synchronise somewhat. This McClintock effect was first described in 1971, and possibly explained by the action of pheromones in 1998. The McClintock effect, also known as menstrual synchrony or the dormitory effect, is a theory that proposes that the Menstrual cycles of women who live A pheromone (from Greek φέρω phero "to bear" + ‘ορμόνη " Hormone " is a Chemical that triggers a natural ^[11] However, subsequent research has called this conclusion into question. ^[12]

Hormonal control

Extreme intricacies regulate the menstrual cycle. For many years, researchers have argued over which regulatory system has ultimate control: the hypothalamus, the pituitary, or the ovary with its growing follicle; but all three systems have to interact. In any scenario, the growing follicle has a critical role: it matures the lining, provides the appropriate feedback to the hypothalamus and pituitary, and modifies the mucus changes at the cervix.

Gonadal

Two sex hormones play a role in the control of the menstrual cycle: estrogen and progesterone:

• Estradiol peaks twice, during follicular growth and during the luteal phase. Sex steroids, also known as gonadal steroids, are Steroid hormones that interact with Vertebrate Androgen or Estrogen receptors Estrogens (US otherwise oestrogens or œstrogens) are a group of Steroid compounds named for their importance in the Estrous cycle, Progesterone is a C-21 Steroid Hormone involved in the Female Menstrual cycle, Pregnancy (supports Gestation
• Progesterone remains virtually absent prior to ovulation, but becomes critical in the luteal phase and during pregnancy. Many tests for ovulation check for the presence of progesterone.

After ovulation the corpus luteum — which develops from the burst follicle and remains in the ovary — secretes both estradiol and progesterone. The corpus luteum ( Latin for "yellow body" (plural corpora lutea) is a temporary Endocrine structure in mammals involved in production of Only if pregnancy occurs do hormones appear in order to suspend the menstrual cycle, while production of estradiol and progesterone continues. Abnormal hormonal regulation leads to disturbance in the menstrual cycle.

Hypothalamus and pituitary

These sex hormones come under the influence of the pituitary gland, and both FSH and LH play necessary roles:

• FSH stimulates immature follicles in the ovaries to grow. The pituitary gland, or hypophysis, is an Endocrine gland about the size of a Pea. Ovarian follicle is the basic unit of female reproductive biology and is composed of a roughly spherical aggregations of cells found in the Ovary.
• LH triggers ovulation.

The gonadotropin-releasing hormone of the hypothalamus controls the pituitary, yet both the pituitary and the hypothalamus receive feedback from the follicle. Gonadotropin-releasing hormone ( GNRH) also known as Luteinizing-hormone releasing hormone ( LHRH) is a tropic Peptide Hormone The hypothalamus links the Nervous system to the Endocrine system via the Pituitary gland (hypophysis

Cyclic effects upon nervous system

Some women with neurological conditions experience increased activity of their conditions at about the same time every month. 80 percent of women with epilepsy have more seizures than usual in the phase of their cycle when progesterone declines and estrogen increases. Epilepsy is a common chronic Neurological disorder that is characterized by recurrent unprovoked seizures. This is called "catamenial epilepsy".

Mice have been used as an experimental system to investigate possible mechanisms by which levels of sex steroid hormones might regulate nervous system function. During the part of the mouse estrous cycle when progesterone is highest, the level of nerve-cell GABA receptor subtype delta was high. Neurons (ˈnjuːɹɒn also known as neurones and nerve cells) are responsive cells in the Nervous system that process and transmit information The GABAA receptor is one of two ligand-gated Ion channels responsible for mediating the effects of Gamma-aminobutyric acid (GABA the major Since these GABA receptors are inhibitory, nerve cells with more delta receptors are less likely to fire than cells with lower numbers of delta receptors. An Inhibitory Postsynaptic Potential (commonly abbreviated as IPSP) is the change in membrane voltage of a postsynaptic Neuron which results from synaptic During the part of the mouse estrous cycle when estrogen levels are higher than progesterone levels, the number of delta receptors decrease, increasing nerve cell activity, in turn increasing anxiety and seizure susceptibility. ^[13]

Hidden ovulation

Main article: Concealed ovulation

Unlike almost all other species, the external physical changes of a human female near ovulation are very subtle. Human females have concealed ovulation or hidden estrus. Most Female animals show distinctive signs when they are " in heat " In contrast, other species often signal receptivity through heat, swellings, and/or changes in color in the genital area. Humans are the only mammal to lack obvious, visible manifestations of ovulation, although some argue that the extended estrus period of the bonobo (reproductive-age females are in heat for 75% of their menstrual cycle)^[14] has a similar effect to the lack of a "heat" in human females. Oestrus is also the biological genus name of the gadfly. The estrous cycle (also oestrous cycle; derived from Latin The Bonobo (bə'noʊboʊ Pan paniscus) until recently usually called the Pygmy Chimpanzee (and less often the Dwarf or Gracile Chimpanzee ^[15]

While women can be taught to recognize their own level of fertility (fertility awareness), whether men can detect fertility in women is highly debated. Fertility awareness (FA refers to a set of practices used to determine the fertile and infertile phases of a woman's Menstrual cycle. On one hand, several small studies have found that fertile women (compared to women in infertile portions of the menstrual cycle or on hormonal contraception) appear more attractive. ^[16][17] On the other hand, two small studies of monogamous couples found that women initiated sex significantly more frequently when fertile, but male-initiated sex occurred at a constant rate in all phases of the menstrual cycle. ^[18]

The ovary as an egg-bank

Evidence suggests that eggs are formed from germ cells early in fetal life. Germ cells are progenitors of the Gametes. These singled out cells move through the gut to the developing Gonads and undergo mitotic proliferation followed The number is reduced to an estimated 400,000 to 450,000 immature ova residing in each ovary at puberty. The menstrual cycle, as a biologic event, allows for ovulation of one egg typically each month. Thus over her reproductive lifetime a woman will ovulate approximately 400 to 450 times. All the other eggs dissolve by a process called atresia. Atresia is a condition in which a body Orifice or passage in the body is abnormally closed or absent As a woman's total egg supply is formed in fetal life,^[19] to be ovulated decades later, it has been suggested that this long lifetime may make the chromatin of eggs more vulnerable to division problems, breakage, and mutation than the chromatin of sperm, which are produced continuously during a man's reproductive life. Chromatin is the complex basis of DNA and protein that makes up Chromosomes It is found inside the nuclei of eukaryotic cells, and within the

Cycle abnormalities

Main article: Menstrual disorder

Anovulation

Apparently normal menstrual flow can occur without ovulation preceding it (anovulatory cycle - "an-" meaning "absence of" +ovulation). A menstrual disorder is an irregular condition in a woman's Menstrual cycle. The anovulatory cycle is a Menstrual cycle characterized by varying degrees of menstrual intervals and the absence of Ovulation and a Luteal phase. In some women, follicular development may start but not be completed; nevertheless, estrogens will form and will stimulate the uterine lining. Anovulatory flow resulting from a very thick endometrium caused by prolonged, continued high estrogen levels is called estrogen breakthrough bleeding. Anovulatory bleeding triggered by a sudden drop in estrogen levels is called estrogen withdrawal bleeding. ^[20]

Anovulatory bleeding may occur on a regular basis, but more commonly happens with irregular frequency. Anovulatory flow commonly occurs prior to menopause (premenopause) or in women with polycystic ovary syndrome. Menopause is the permanent shutting down of the female Reproductive system, a considerable length of time before the end of the lifespan Polycystic ovary syndrome abbreviated PCOS or PCO (also known clinically as Stein-Leventhal syndrome, Sclerocystic ovary syndrome, Hyperthecosis

Infrequent or irregular ovulation is called oligoovulation.

Flow

Sudden heavy flows or amounts in excess of 80 ml (hypermenorrhea or menorrhagia) are not normal. Menorrhagia is an abnormally heavy and prolonged menstrual period at regular intervals

Very little flow (less than 10ml) is called hypomenorrhea.

Prolonged flow (metrorrhagia, also meno-metrorrhagia) no longer shows a clear interval pattern. Dysfunctional uterine bleeding refers to hormonally caused flow abnormalities, typically anovulation. Dysfunctional Uterine Bleeding (DUB is the most common cause of functional abnormal uterine bleeding which is abnormal genital tract bleeding based in the Uterus

All bleeding abnormalities need medical attention; they may indicate hormone imbalances, uterine fibroids, or other problems. As pregnant patients may bleed, a pregnancy test forms part of the evaluation of abnormal flow. A pregnancy test attempts to determine whether or not a female is pregnant.

Cycle length

The medical term for cycles with intervals of 21 days or fewer is polymenorrhea and, on the other hand, the term for cycles with intervals exceeding 35 days is oligomenorrhea (or amenorrhea if intervals exceed 180 days). A menstrual disorder is an irregular condition in a woman's Menstrual cycle. Oligomenorrhea is the medical term for infrequent uterine bleeding episodes with intervals of more than 35 days Amenorrhoea ( BE) amenorrhea ( AmE) or amenorrhœa, is the absence of a Menstrual period in a woman of reproductive age

Amenorrhea refers to a prolonged absence of menses during the reproductive years of a woman. Amenorrhoea ( BE) amenorrhea ( AmE) or amenorrhœa, is the absence of a Menstrual period in a woman of reproductive age For example, women with very low body fat, such as athletes, may cease to menstruate. "Adipose" redirects here For the Doctor Who monster see " Partners in Crime " A sportsperson ( British and American English) or athlete (principally American English is any person who participates regularly in a Sport. Amenorrhea also occurs during pregnancy.

Early menarche

The condition precocious puberty has caused menstruation to occur in girls as young as eight months old. Precocious puberty (La pubertas praecox) is an unusually early onset of Puberty, the process of sexual maturation triggered by the brain or exogenous chemicals which ^[21]

Contraception and menstruation

Hormonal options

Main article: Hormonal contraception

Estrogens and progesterone-like hormones make up the main active ingredients of hormonal birth control methods such as the pill. Hormonal contraception refers to Birth control methods that act on the hormonal system Typically they cause regular monthly flow that roughly mimics a menstrual cycle in appearance, but suppresses ovulation. With most pills, a woman takes hormone pills for 21 days, followed by 7 days of non-functional placebo pills or no pills at all, then the cycle starts again. During the 7 placebo days, a withdrawal bleeding occurs; this differs from ordinary menstruation, and skipping the placebos and continuing with the next batch of hormone pills may suppress it. (There are two main versions of the pill: monophasic and triphasic. With triphasic pills, skipping placebos and continuing with the next month's dose can make a woman more likely to experience spotting or breakthrough bleeding. Breakthrough bleeding is Bleeding while taking the active pills of combined oral contraceptives, or other hormonal contraceptives ) In 2003, the U. S. Food and Drug Administration (FDA) approved low-dose monophasic birth control pills that induce withdrawal bleeding every 3 months. Yet another version of the pill is the Loestrin Fe, which has only a four-day placebo "week" (the placebos are actually iron supplements intended to replenish iron lost by uterine shedding); the other three placebos are replaced with active hormone pills. This system is intended to help shorten periods. Mircette contains several days of estrogen-only pills in addition to the usual combination estrogen/progestin pills, in the case of women who may have problems with low estrogen during the placebo days with other pills. Oral contraceptives come in a variety of formulations The main division is between Combined oral contraceptive pills containing both Estrogen and synthetic Progestogens

Other types of hormonal birth control which affect menstruation include the vaginal Nuvaring and the transdermal patch (like the standard pill pack, active hormones are given for three weeks, followed by a one-week break to allow blood flow) and the injection (which can eliminate all flow as long as the injections are taken every twelve weeks, although spotting is a common side effect). NuvaRing is the trade name for a combined hormonal Contraceptive Vaginal ring manufactured by Organon that is available by prescription A contraceptive patch is a Transdermal patch applied to the skin that releases synthetic Estrogen and Progestin hormones to prevent Pregnancy Depot medroxyprogesterone acetate ( DMPA) is a Progestin -only hormonal contraceptive Birth control drug which is injected every 3 months

Effects on menstruation

All such methods are designed to regulate the monthly blood flow. Because of this, they are often chosen by females who wish to regulate the frequency and length of their period, often for basic convenience and especially when such factors are irregular and problematic on their own. Hormonal contraception has also been shown to improve menstrual symptoms such as cramping, heavy flow, and other bothersome physical and emotional issues related to periods.

Control and flexibility

Hormonal methods which are controlled by the user day-to-day, including pills, the ring, and the patch, need not always be used according to the standard cycle/calendar. Their use can be rescheduled and altered in various ways to postpone or skip periods when desired for reasons of convenience (e. g. , traveling or scheduled gynecological exams), personal enjoyment (such as expected sexual encounters or events like a wedding or dance), or health (including very painful periods or sensitivity to hormone fluctuations). Similarly, abrupt cessation of use can induce a breakthrough period mid-cycle.

Other contraceptive methods

Most IUDs are not designed to affect menstruation or breakthrough bleeding, but may exacerbate cramps or the heaviness of the flow due to their placement within the uterus. An intrauterine device ( intra meaning within, and uterine meaning of the Uterus) is a Birth control device placed The Mirena IUD releases a small continuous dosage of a progesterone-like hormone, which can sometimes cause menstruation to cease. Tubal sterilization alone will not affect menstruation, though the ablation option often performed at the same time will cause menstruation to cease. Tubal ligation (informally known as getting one's "tubes tied" is a permanent form of female sterilization, in which the Fallopian tubes are severed Endometrial ablation is a Medical procedure that is used to remove ( ablate) or destroy the endometrial lining of a woman's Uterus. Hysterectomy will, of course, completely stop menstruation as it entails the removal of the uterus (and sometimes the ovaries, fallopian tubes, and cervix). A hysterectomy (from Greek hystera "womb" is the surgical removal of the Uterus, usually performed by a gynecologist. The uterus (from the Latin word for womb) is the major Female reproductive organ of most Mammals including Humans One end the Fertility awareness methods do not affect the period in and of themselves, but involve careful observation of various kinds, of which the timing of the period is an essential factor. Fertility awareness (FA refers to a set of practices used to determine the fertile and infertile phases of a woman's Menstrual cycle.

Menstruation and the moon

See also: Culture and menstruation

Traditional sources agree that the menstrual cycle is linked to the cycle of the moon. The relationship between culture and menstruation is expressed in many ways These sources generally indicate that women menstruate at the time of the new moon, and ovulate at the full moon. Although scientific evidence for this has been weak, the problem may be that most women today live in urban environments where the moon is no longer a significant contributor to nocturnal light. The fact that women who work on night shifts, where they are exposed to strong light at night, often experience menstrual irregularities, is just one example of how rhythms of light and darkness do influence hormonal physiology, including the menstrual cycle. ^[22]

The word "menstruation" is etymologically related to moon. The terms "menstruation" and "menses" come from the Latin mensis (month), which in turn relates to the Greek mene (moon) and to the roots of the English words month and moon — reflecting the fact that the moon also takes close to 28 days to revolve around the Earth (actually 27. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly 32 days). The synodical lunar month, the period between two new moons (or full moons), is 29. In Lunar calendars a lunar month is the time between two identical syzygies ( New moons or Full moons. 53 days long.

A 1975 book by Louise Lacey documented the experience of herself and 27 of her friends, who found that when they removed all artificial night lighting their menstrual cycles began to occur in rhythm with the lunar cycle. She dubbed the technique Lunaception. Lunaception is a form of Menstrual cycle regulation and in some cases natural birth control and conception aid that depends upon the woman practicing it to align her ^[23] Later studies in both humans^[24] and animals^[25] have found that artificial light at night does influence the menstrual cycle in humans and the estrus cycle in mice (cycles are more regular in the absence of artificial light at night), though none have duplicated the synchronization of women's menstrual cycles with the lunar cycle. One author has suggested that sensitivity of women's cycles to nightlighting is caused by nutritional deficiencies of certain vitamins and minerals. ^[26]

Some have suggested that the fact that other animals' menstrual cycles appear to be greatly different from lunar cycles is evidence that the average length of humans' cycle is most likely a coincidence. ^[27][28]

Menstrual cycles in other mammals

Females of most species advertise ovulation to males with visual cues and behavioral cues, pheromones, or both (humans are a species that does not). A pheromone (from Greek φέρω phero "to bear" + ‘ορμόνη " Hormone " is a Chemical that triggers a natural Human females have concealed ovulation or hidden estrus. Most Female animals show distinctive signs when they are " in heat " This period of advertised fertility is known as estrus or heat. However, in animals with menstrual cycles, females can be sexually active at any time in their cycle, even when they are not in heat. Great apes' cycles vary in length from an average of 29 days in orangutans to an average of 37 days in chimpanzees. The orangutans are two Species of great apes known for their intelligence long arms and reddish-brown hair Chimpanzee (often shortened to chimp) is the common name for the two extant Species of Apes in the Genus Pan.

By contrast, in species that have estrous cycles rather than menstrual cycles, females are only receptive to copulation while they are in heat (dolphins are an exception). Oestrus is also the biological genus name of the gadfly. The estrous cycle (also oestrous cycle; derived from Latin Dolphins are Marine mammals that are closely related to Whales and Porpoises There are almost forty species of dolphin in seventeen genera. The other significant difference is that in an estrous cycle, if no fertilization takes place, the uterus reabsorbs the endometrium: no menstrual blood flow occurs. Some animals, such as domestic cats and dogs, experience small amounts of bleeding while in heat. WikipediaManual of Style (spelling, articles should conform to one overall spelling style of English typically the one most linked to the article topic (if it is geographic The dog ( Canis lupus familiaris) is a domesticated Subspecies of the gray wolf, a Mammal of the Canidae family of the order This phase of the estrous cycle corresponds most closely to the follicular phase of the menstrual cycle and should not be confused with menstruation.

References

Notes

External links

• Museum of Menstruation and Women's Health
• Centre for Menstrual Cycle and Ovulation Research
• Society for Menstrual Cycle Research
• TREMIN Trust archive of menstrual cycle data

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