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Menarche (IPA: /məˈnɑrki/) is the first menstrual period, or first menstrual bleeding in the females of human beings. The menstrual cycle is a recurring cycle of physiologic changes that occurs in reproductive-age Females Overt menstruation (where there is blood flow from the Human beings, humans or man (Origin 1590–1600 L homō man OL hemō the earthly one (see Humus From both social and medical perspectives it is often considered the central event of female puberty, as it signals the possibility of fertility. Fertility is the natural capability of giving life As a measure "Fertility Rate" is the number of children born per couple person or population Timing of menarche is influenced by both genetic and environmental factors, especially nutritional status. The average age of menarche has declined over the last century but the magnitude of the decline and the factors responsible remain subjects of contention. The average age of menarche in the United States is about 12 years and 5 months. The United States of America —commonly referred to as the [1]

Contents

Physiologic aspects

Menarche as part of puberty

Menarche is the culmination of a series of physiological and anatomic processes of puberty:

A specific hormonal signal for menarche is not known; menarche as a discrete event is thought to be the relatively chance result of the gradual thickening of the endometrium induced by rising but fluctuating pubertal oestrogen.

The menstruum, or "flow," consists of a combination of fresh and clotted blood with endometrial tissue. The initial flow of menarche is usually brighter red than mature menstrual flow. It is often scanty in amount and may be very brief, even a single instance of "spotting. " Like other menses, menarche may be accompanied by abdominal cramping. Abdominal pain can be one of the Symptoms associated with transient disorders or serious disease

Menarche and fertility

In most girls, menarche does not signal that ovulation has occurred. Note This article deals primarily with Human ovulation nonhuman Animal ovulation is touched on briefly at the conclusion Studies of American girls suggest that the average interval between menarche and ovulation is several months. Irregular, anovulatory menses commonly occur for 1-2 years or more before regular ovulation is established.

Regular ovulation is usually indicated by predictable and consistent intervals between menses, predictable and consistent durations of menses, and predictable and consistent patterns of flow (e. g. , heaviness or cramping). Continuing ovulation typically requires a body fat content of at least 22%. An anthropological term for this state of potential fertility is nubility. Anthropology (/ˌænθɹəˈpɒlədʒi/ from Greek grc ἄνθρωπος anthrōpos, "human" -λογία -logia) is the study of Nubility is the state of being marriageable In a given Society, the level of nubility (those eligible for marriage compared to the level of Nuptiality (state of

On the other hand, not every girl follows the typical pattern, and some girls ovulate before the first menstruation. Although unlikely, it is possible for a girl who has engaged in sexual intercourse shortly before her menarche to conceive and become pregnant, which would delay her menarche until after the birth. 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 Controversy over the beginning of pregnancy usually occurs in the context of the Abortion debate Pregnancy ( Latin graviditas) is the carrying of one or more offspring known as a Fetus or Embryo, inside the Uterus of a Female This goes against the widely held assumption that a woman cannot become pregnant until after menarche.

Effects of stress and social environment on timing of menarche

Some of the least understood environmental influences on timing of puberty are social and psychological. Nearly all of the research on these effects has concerned girls, partly because female puberty requires greater physiologic resources and partly because it involves a unique event (menarche) that makes survey research into female puberty much simpler than male. In most of these studies menarche was specifically examined, assuming it to be a valid "proxy" for the more general process of puberty. In comparison with the effects of genetics, nutrition, and general health, social influences are small, shifting timing by a few months rather than years. The most important part of a child's psychosocial environment is the family.

Some of the aspects of family structure and function reported to be independently associated with earlier menarche:

Some of the aspects of family structure and function reported to be independently associated with later menarche:

Other research has focused on the effect of childhood stress on timing of puberty, especially female. Stress is a vague term and studies have examined conditions ranging from family tensions or conflict to wartime refugee status with threat to physical survival. The more dire social conditions have been found to be associated with delay of maturation, an effect that may be compounded by dietary inadequacy. There is more uncertainty and mixed evidence as to whether milder degrees of stress or early-life undernutrition can accelerate puberty in girls as would be predicted by life history theory and demonstrated in many other mammals. Life history theory is an analytical framework widely used in animal and human Biology, Psychology, and Evolutionary Anthropology which postulates

The understanding of these environmental effects is incomplete and the following observations and cautions are relevant:

Changes over time in the average age of menarche

There were few systematic studies of timing of menarche before the latter half of the 20th century. Most older estimates of average timing of menarche were based on observation of a small homogeneous population not necessarily representative of the larger population, or based on recall by adult women, which is also susceptible to various forms of error. Most sources agree that the average age of menarche in girls in modern societies has declined, though the reasons and the degree remain subjects of controversy. There have been claims of a 2- to 2. 5-year decline from about 1900 to the 1960s, but the best North American surveys reported only a 2-3 month decline from the mid-1970s to the mid-1990s. This is commonly attributed to larger body size and earlier average attainment of sufficient body fat, but other factors such as environmental exposure to chemicals that mimic oestrogen or the urbanization and/or sexualization of Western society have also been considered as contributing factors.

Less than 10% of U. S. girls start to menstruate before 11 years of age, and 90% of all US girls are menstruating by 13. 75 years of age, with a median age of 12. 43 years. This age at menarche is not significantly different (0. 34 years earlier) than that reported for U. S. girls in 1973. Age at menarche for non-Hispanic black girls was significantly earlier than that of white girls at 10%, 25%, and 50% of those who had attained menarche, whereas Mexican American girls were only significantly earlier than the white girls at 25%. [2]

Cultural aspects of menarche

Menarche is celebrated in many cultures around the world as a rite of passage, a time to recognize that a girl is moving into womanhood. A rite of passage is a Ritual that marks a change in a person's social or sexual status

Rites of passage

Some cultures have in past centuries have had rites of passage for a girl experiencing menarche.

Africa

Asia, Australia, and Pacific Islands

North America

Medical aspects of menarche

When menarche occurs, it confirms that the girl has had a gradual oestrogen-induced growth of the uterus, especially the endometrium, and that the "outflow tract" from the uterus, through the cervix to the vagina, is open. Estrogens (US otherwise oestrogens or œstrogens) are a group of Steroid compounds named for their importance in the Estrous cycle, The uterus (from the Latin word for womb) is the major Female reproductive organ of most Mammals including Humans One end the The endometrium is the inner membrane of the Mammalian Uterus. The cervix (from Latin "neck" is the lower narrow portion of the Uterus where it joins with the top end of the Vagina. The vagina (from Latin, literally " Sheath " or " Scabbard " is a fibromuscular tubular tract leading from the Uterus

In very rare instances, menarche may occur at an unusually early age, preceding thelarche and other signs of puberty. Thelarche is the first stage of secondary (postnatal Breast development usually occurring at the beginning of Puberty in girls This is termed isolated premature menarche, but other causes of bleeding must be investigated and excluded. Growth is usually normal. [3] Isolated premature menarche is rarely the first manifestation of precocious puberty. 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

When menarche has failed to occur for more than 3 years after thelarche, or beyond 16 years of age, the delay is referred to as primary amenorrhea. Amenorrhoea ( BE) amenorrhea ( AmE) or amenorrhœa, is the absence of a Menstrual period in a woman of reproductive age

See also

References

  1. ^ Relative Weight and Race Influence Average Age at Menarche: Results From Two Nationally Representative Surveys of US Girls Studied 25 Years Apart - Anderson et al. 111 (4): 844 - Pediatrics
  2. ^ Chumlea WC, Schubert CM, Roche AF, Kulin HE, Lee PA, Himes JH, Sun SS (2003 Jan). Puberty is described as delayed when a boy or girl has passed the usual age of onset of Puberty with no physical or hormonal signs that it is beginning The first ejaculatory experience of boys is termed spermarche. Thelarche is the first stage of secondary (postnatal Breast development usually occurring at the beginning of Puberty in girls Adrenarche refers to a stage of maturation of the cortex of the human Adrenal glands It typically occurs between ages 6 and 10 years and involves both structural and functional Pubarche refers to the first appearance of Pubic hair in a child Gonadarche refers to the earliest Gonadal changes of Puberty. The menstrual cycle is a recurring cycle of physiologic changes that occurs in reproductive-age Females Overt menstruation (where there is blood flow from the Lina Medina (born September 27 1933) is the youngest confirmed mother in medical history, giving birth at the age of 5 years 7 months and 21 days "Age at menarche and racial comparisons in US girls., 2005. PMID 12509562". Lifespan Health Research Center, Department of Community Health, Wright State University, School of Medicine, Dayton, Ohio, USA.  
  3. ^ R. Stanhope, C. Traggiai (2006). Isolated Menarche. Precocious Puberty (Complete, Partial). Armenian Health Network, Health. am. Retrieved on 2006-11-26. Year 2006 ( MMVI) was a Common year starting on Sunday of the Gregorian calendar. Events 43 BC - The Second Triumvirate alliance of Gaius Julius Caesar Octavianus ("Octavian" later "Caesar Augustus"

Further reading

External links

Dictionary

menarche

-noun

  1. The onset of menstruation; the beginning of the menstrual period. A girl's first period.
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