Menarche
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Menarche (
Girls experience menarche at different ages.[1][2] Having menarche occur between the ages of 9–14 in the West is considered normal.[3] Canadian psychological researcher Niva Piran claims that menarche or the perceived average age of puberty is used in many cultures to separate girls from activity with boys, and to begin transition into womanhood.[4]
The timing of menarche is influenced by female biology, as well as genetic and environmental factors, especially nutritional factors.[5] The mean age of menarche has declined over the last century, but the magnitude of the decline and the factors responsible remain subjects of contention. The worldwide average age of menarche is very difficult to estimate accurately, and it varies significantly by geographical region, race, ethnicity and other characteristics, and occurs mostly during a span of ages from 8 to 16, with a small percentage of girls having menarche by age 10, and the vast majority having it by the time they were 14.[3] There is a later age of onset in Asian populations compared to the West, but it too is changing with time. For example a Korean study in 2011 showed an overall average age of 12.7, with around 20% before age 12, and more than 90% by age 14.[6] A Chinese study from 2014 published in Acta Paediatrica showed similar results (overall average of age 12.8 in 2005 down to age 12.3 in 2014) and a similar trend in time, but also similar findings about ethnic, cultural, and environmental effects.[7]
The average age of menarche was about 12.7 years in
Physiology
Puberty
Menarche is the culmination of a series of
- Attainment of a sufficient body mass (typically 17% body fat).[12]
- Disinhibition of the
- Secretion of pituitary hormones.
- Over an interval of about 2 to 3 years, estrogen stimulates growth of the pelvis, and increased regional adipose tissue).
- Estrogen stimulates growth and vascularity of the endometrium, the lining of the uterus.
- Fluctuations of hormone levels can result in changes of adequacy of blood supply to parts of the endometrium.
- Death of some of the endometrial tissue from these hormone or blood supply fluctuations leads to deciduation, a sloughing of part of the lining with some blood flow from the vagina.
No specific hormonal signal for menarche is 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 estrogen.[citation needed]
The menstruum, or flow, consists of a combination of fresh and clotted blood with endometrial tissue. The initial flow of menarche is usually brighter 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.[citation needed]
Relation to fertility
In most girls, menarche does not mean that
On the other hand, not every girl follows the typical pattern, and some girls ovulate before the first
Onset
When menarche occurs, it confirms that the girl has had a gradual estrogen-induced growth of the uterus, especially the endometrium, and that the "outflow tract" from the uterus, through the cervix to the vagina, is open.
When a woman experiences menarche, the blood flow can vary from a slow and spotty discharge to a consistent blood flow for 3–7 days. While the color of the blood does range from a brown to bright red color, this is normal; some women have light periods while others have heavy ones; no two women will have an identical experience.[16]
In very rare instances, menarche may occur at an unusually early age, preceding thelarche and other signs of puberty. This is termed isolated premature menarche, but other causes of vaginal bleeding must be investigated and excluded. Growth is usually normal.[17] Isolated premature menarche is rarely the first manifestation of precocious puberty.[citation needed]
When menarche has failed to occur for more than three years after thelarche, or beyond 16 years of age, the delay is referred to as
Timing
Chronic illness
Certain systemic or chronic illness can delay menarche, such as undiagnosed and untreated
Conditions and disease states
Studies have been conducted to observe the association of the timing of menarche with various conditions and diseases. Some studies have shown that there may be an association between early or late-age menarche and cardiovascular disease, although the mechanism of the association is not well understood.[27] A systematic review has concluded that early age at menarche is also a risk factor for the insulin resistance condition.[28] There is conflicting evidence regarding the association between obesity and timing of menarche; a meta-analysis and systematic review has determined that more studies must be conducted to make any definitive conclusions about this association.[29]
Effects of stress and social environment
Some of the aspects of family structure and function reported to be independently associated with earlier menarche [antenatal and early childhood]
- Being non-white (in the UK)[30]
- Having experienced pre-eclampsia in the womb[30]
- Being a singleton, i.e. not a twin, triplet, etc.[30]
- Low birthweight[30]
- Not having been breast-fed[30]
- Previous exposure to smoking[30]
- High-conflict family relationships[31]
- Increased incidence of childhood obesity.[30]
- Lack of exercise in childhood[30]
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 under-nutrition can accelerate puberty in girls as would be predicted by life history theory and demonstrated in many other mammals.[32]
The understanding of these environmental effects is incomplete and the following observations and cautions are relevant:
- Mechanisms of these social effects are unknown, though a variety of physiological processes, including pheromones, have been suggested based on animal research.
- Most of these "effects" are statistical associations revealed by epidemiologic surveys. Statistical associations are not necessarily causal, and a variety of secondary variables and alternative explanations can be possibly intervening. Effects of such small size can never be confirmed or refuted for any individual child.
- Despite the small magnitude of effect, interpretations of the data are politically controversial because of the ease with which this type of research can be used for political advocacy. Accusations of bias based on political agenda sometimes accompany scientific criticism.
- Correlation does not imply causation. While correlation can be objectively measured, causation is statistically inferred. Some suggest that childhood stress is caused by precocious puberty recognized later, rather than being the cause of it.[33]
Changes in time of average age
This article appears to contradict the article Puberty. (March 2021) |
There were few systematic studies of timing of menarche before the later 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. From the sixth to the fifteenth centuries in Europe, most women reached menarche on average at about 14, between the ages of 12 and 15.
This is called the secular trend.[38][39]
Fewer than 10% of U.S. girls start to menstruate before 11 years of age, and 90% of all U.S. girls are menstruating by 13.8 years of age, with a median age of 12.4 years. This age at menarche is not much different (0.3 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 non-white Mexican American girls were only slightly earlier than the white girls at 25%.[40]
Culture
Menstruation is a cultural as well as scientific phenomenon as many societies have specific rituals and cultural norms associated with it. These rituals typically begin at menarche and some are enacted during each menstruation cycle. The rituals are important in determining a status change for girls. Upon menarche and completion of the ritual, they have become a woman as defined by their culture.
For young women in many cultures, the first menstruation is a marker that signifies a change in status. Post-menarche, the young woman enters a stage called maidenhood, the stage between menarche and marriage.[41] There are cultures that have in past centuries, and in present, practiced rites of passage for a girl experiencing menarche.[42]
Celebratory ceremonies
In some cultures, a party, or celebration is thrown to show the girl's transition to womanhood. This party is similar to the quinceañera in Latin America, except that a specific age marks the transition rather than menarche. In Morocco, the girl is thrown a celebration. All of her family members are invited and the girl is showered with money and gifts.
When a
In some
The Mescalero Apaches place high importance on their menarche ceremony and it is regarded as the most important ritual in their tribe. Each year, there is an eight-day event celebrating all of the girls who have menstruated in the past year. The days are split between feasting and private ceremonies reflecting on their new womanly status.[45]
Rituals of learning
In
In the United States, some public schools have a sex education program that teaches girls about menstruation and what to expect at the onset of menarche (often this takes place during the fourth grade). Historically menstruation has been a social taboo and girls were taught about menarche and menstruation by their mothers or a female role model. Then, and to an extent now, menstruation was a private matter and a girl's menarche was not a community phenomenon.[46]
Rituals of cleansing or purification
The
In
In
Rituals of transformation and scarification
In Nigeria, the Tiv ethnic group cut four lines into the abdomen of their girls during menarche. The lines are supposed to represent fertility.[43]
Rituals of strength
The
The
Movies and TV
In the horror movie Carrie (1976), an adaptation of the Stephen King novel of the same name, protagonist Carrie White experiences her first period as she showers after the school gym class. Unaware of what is happening to her, she panics and pleads for help, but the other girls respond by bullying her. Carrie's first period unleashes her violent powers and is central to her dangerous and out of control transformation.[48] This theme is common to horror movies, another notable example being the Canadian horror movie Ginger Snaps (2000), where the protagonist's first period is central to her gradual transformation into a werewolf. The theme of transformation around the menarche is similarly present in Turning Red (2022), although the film also explores other aspects of puberty as a whole and the protagonist does not actually start her first period. Girls experiencing their first period is part of many movies, particularly ones that include coming-of-age plot lines, such as The Blue Lagoon (1980), The Company of Wolves (1984), An Angel at My Table (1990), My Girl (1991), Return to the Blue Lagoon (1991), Eve’s Bayou (1997), and A Walk on the Moon (1999). Menarche is also discussed in an episode of the animated series Baymax! (2022) in which the eponymous healthcare robot helps a girl deal with her first period.
See also
- Adrenarche
- Delayed puberty
- Gonadarche
- Lina Medina, who had her menarche at age 8 months and is the youngest mother in history
- Menopause, the equivalent opposite change at the end of the child-bearing years
- Pubarche
- Spermarche
- Thelarche
References
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- ^ https://www.cdc.gov/nchs/data/nhsr/nhsr146-508.pdf[bare URL PDF]
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- PMID 29261991. Retrieved 2021-03-21.
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- ^ "First period: Early signs, how long it lasts, and self-care tips". www.medicalnewstoday.com. 2021-01-27. Retrieved 2022-03-21.
- ^ R. Stanhope; C. Traggiai (2006). "Isolated Menarche". Precocious Puberty (Complete, Partial). Armenian Health Network. Retrieved 2006-11-26.
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- ^ The Australian, 3 April 2013. Early onset puberty causes emotional issues at preschool age Archived April 16, 2013, at the Wayback Machine
- ^ Boaz, N.T. (1999):
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The sequence and age range of the developmental changes associated with puberty can vary widely. Although most children begin puberty between the ages of 10 and 12, it can start at any age from 8 to 16. The most obvious determining factor is gender; on average, puberty arrives earlier for girls than boys. Heredity also appears to play an important role. Compared to an overall age range of nine to 18 for menarche, the age difference for sisters averages only 13 months and for identical twins, less than three months. Body weight is a factor as well: puberty often begins earlier in heavier children of both sexes and later in thinner ones. The onset of menstruation, in particular, appears to be related to amounts of body fat. Girls with little body fat, especially athletes, often start menstruating at a later than-average age. Over the past 100 years, puberty has tended to begin increasingly early in both sexes (a phenomenon called the secular trend).
- ISBN 0-7876-4786-1.
The timing of physical maturation varies widely. In the United States today, menarche, the first menstrual period, typically occurs around age 12, although some youngsters start puberty when they are only eight or nine, others when they are well into their teens. The duration of puberty also varies greatly: eighteen months to six years in girls and two to five years in boys.
- PMID 12509562.
- ISBN 978-0-202-30321-5.
- ^ Hartman, Holly. Girlwonder: Every Girl's Guide to the Fantastic Feats, Cool Qualities, and Remarkable Abilities of Women and Girls. Boston: Houghton Mifflin, 2003.
- ^ ISBN 978-0395694589. Retrieved 2013-11-09.
- ^ Chockalingam K (1973). Census of India, 1971: A. General report. Retrieved 2013-11-09.
- ISBN 9781576075173. Retrieved 2013-11-09.
- ISBN 978-0801892455. Retrieved 2013-11-09.
- ^ Tal I (2004). Exploring the Meaning of Becoming a Woman in Non-Western Culture: A narrative Analysis of First Menstruation Stories of Ethiopian Jewish Women. p. 64.
- ^ Charisma, Tina (April 1, 2021). "A Brief History of Onscreen Periods". Vulture. Archived from the original on April 1, 2021. Retrieved August 31, 2022.
Further reading
- Gluckman PD, Hanson MA (January 2006). "Evolution, development and timing of puberty". Trends in Endocrinology and Metabolism. 17 (1): 7–12. S2CID 26141301.
- Quinlan R (2003). "Father absence, parental care, and female reproductive development" (PDF). Evolution and Human Behavior. 24 (6): 376–90. doi:10.1016/S1090-5138(03)00039-4. Archived from the original(PDF) on 2017-08-09. Retrieved 2022-02-21.