Menarche
Encyclopedia
Menarche is the first menstrual cycle
, or first menstrual bleeding, in female human beings. From both social and medical perspectives it is often considered the central event of female puberty
, as it signals the possibility of fertility
.
Girls experience menarche at different ages. The timing of menarche is influenced by female biology
, as well as genetic
and environmental factor
s, especially nutritional factors. 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 worldwide average age of menarche is very difficult to estimate accurately, and it varies significantly by geographical region, race, ethnicity and other characteristics. Various estimates have placed it at 13.0 Some estimates suggest that the median
age of menarche worldwide is 14, and that there is a later age of onset in Asian
populations compared to the West. The average age of menarche is about 12.5 years in the United States
, 12.72 in Canada
, 12.9 in the UK and 13.06 ± 0.10 years in Iceland
. A study on girls in Istanbul
, Turkey
, found the median age at menarche to be 12.74 years.
:
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 estrogen.
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
.
has occurred. In postmenarchal girls, about 80% of the cycles were anovulatory in the first year after menarche, 50% in the third and 10% in the sixth year. 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.
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. This goes against the widely held assumption that a woman cannot become pregnant until after menarche.
-induced growth of the uterus
, especially the endometrium
, and that the "outflow tract" from the uterus, through the cervix
to the vagina
, is open.
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 bleeding must be investigated and excluded. Growth is usually normal. Isolated premature menarche is rarely the first manifestation of precocious puberty
.
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.
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.
The understanding of these environmental effects is incomplete and the following observations and cautions are relevant:
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 much 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 slightly earlier than the white girls at 25%.
, a time to recognize that a girl is moving into womanhood.
Africa
Asia, Australia, and Pacific Islands
North America
Menstrual cycle
The menstrual cycle is the scientific term for the physiological changes that can occur in fertile women for the purpose of sexual reproduction. This article focuses on the human menstrual cycle....
, or first menstrual bleeding, in female human beings. From both social and medical perspectives it is often considered the central event of female puberty
Puberty
Puberty is the process of physical changes by which a child's body matures into an adult body capable of reproduction, as initiated by hormonal signals from the brain to the gonads; the ovaries in a girl, the testes in a boy...
, as it signals the possibility of fertility
Fertility
Fertility is the natural capability of producing offsprings. As a measure, "fertility rate" is the number of children born per couple, person or population. Fertility differs from fecundity, which is defined as the potential for reproduction...
.
Girls experience menarche at different ages. The timing of menarche is influenced by female biology
Biology
Biology is a natural science concerned with the study of life and living organisms, including their structure, function, growth, origin, evolution, distribution, and taxonomy. Biology is a vast subject containing many subdivisions, topics, and disciplines...
, as well as genetic
Genetics
Genetics , a discipline of biology, is the science of genes, heredity, and variation in living organisms....
and environmental factor
Environmental factor
Environmental factor or ecological factor or ecofactor is any factor, abiotic or biotic, that influences living organisms.- Environmental factors inducing diseases :...
s, especially nutritional factors. 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 worldwide average age of menarche is very difficult to estimate accurately, and it varies significantly by geographical region, race, ethnicity and other characteristics. Various estimates have placed it at 13.0 Some estimates suggest that the median
Median
In probability theory and statistics, a median is described as the numerical value separating the higher half of a sample, a population, or a probability distribution, from the lower half. The median of a finite list of numbers can be found by arranging all the observations from lowest value to...
age of menarche worldwide is 14, and that there is a later age of onset in Asian
Asia
Asia is the world's largest and most populous continent, located primarily in the eastern and northern hemispheres. It covers 8.7% of the Earth's total surface area and with approximately 3.879 billion people, it hosts 60% of the world's current human population...
populations compared to the West. The average age of menarche is about 12.5 years in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, 12.72 in Canada
Canada
Canada is a North American country consisting of ten provinces and three territories. Located in the northern part of the continent, it extends from the Atlantic Ocean in the east to the Pacific Ocean in the west, and northward into the Arctic Ocean...
, 12.9 in the UK and 13.06 ± 0.10 years in Iceland
Iceland
Iceland , described as the Republic of Iceland, is a Nordic and European island country in the North Atlantic Ocean, on the Mid-Atlantic Ridge. Iceland also refers to the main island of the country, which contains almost all the population and almost all the land area. The country has a population...
. A study on girls in Istanbul
Istanbul
Istanbul , historically known as Byzantium and Constantinople , is the largest city of Turkey. Istanbul metropolitan province had 13.26 million people living in it as of December, 2010, which is 18% of Turkey's population and the 3rd largest metropolitan area in Europe after London and...
, Turkey
Turkey
Turkey , known officially as the Republic of Turkey , is a Eurasian country located in Western Asia and in East Thrace in Southeastern Europe...
, found the median age at menarche to be 12.74 years.
As part of puberty
Menarche is the culmination of a series of physiological and anatomic processes of pubertyPuberty
Puberty is the process of physical changes by which a child's body matures into an adult body capable of reproduction, as initiated by hormonal signals from the brain to the gonads; the ovaries in a girl, the testes in a boy...
:
- Attainment of a sufficient body mass (typically 17% body fat).
- Disinhibition of the GnRH pulse generator in the arcuate nucleusArcuate nucleusThe arcuate nucleus is an aggregation of neurons in the mediobasal hypothalamus, adjacent to the third ventricle and the median eminence...
of the hypothalamusHypothalamusThe Hypothalamus is a portion of the brain that contains a number of small nuclei with a variety of functions... - Secretion of estrogenEstrogenEstrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...
by the ovariesOvaryThe ovary is an ovum-producing reproductive organ, often found in pairs as part of the vertebrate female reproductive system. Ovaries in anatomically female individuals are analogous to testes in anatomically male individuals, in that they are both gonads and endocrine glands.-Human anatomy:Ovaries...
in response to pituitary hormoneHormoneA hormone is a chemical released by a cell or a gland in one part of the body that sends out messages that affect cells in other parts of the organism. Only a small amount of hormone is required to alter cell metabolism. In essence, it is a chemical messenger that transports a signal from one...
s. - Over an interval of about 2 to 3 years, estrogen stimulates growth of the uterusUterusThe uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
(as well as height growth, breastBreastThe breast is the upper ventral region of the torso of a primate, in left and right sides, which in a female contains the mammary gland that secretes milk used to feed infants.Both men and women develop breasts from the same embryological tissues...
growth, widening of the pelvis, and increased regional adipose tissueAdipose tissueIn histology, adipose tissue or body fat or fat depot or just fat is loose connective tissue composed of adipocytes. It is technically composed of roughly only 80% fat; fat in its solitary state exists in the liver and muscles. Adipose tissue is derived from lipoblasts...
). - Estrogen stimulates growth and vascularity of the endometriumEndometrium-Function:The endometrium is the innermost glandular layer and functions as a lining for the uterus, preventing adhesions between the opposed walls of the myometrium, thereby maintaining the patency of the uterine cavity. During the menstrual cycle or estrous cycle, the endometrium grows to a...
, 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 vaginaVaginaThe vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...
.
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 estrogen.
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
Abdominal pain can be one of the symptoms associated with transient disorders or serious disease. Making a definitive diagnosis of the cause of abdominal pain can be difficult, because many diseases can result in this symptom. Abdominal pain is a common problem...
.
Relation to fertility
In most girls, menarche does not signal that ovulationOvulation
Ovulation is the process in a female's menstrual cycle by which a mature ovarian follicle ruptures and discharges an ovum . Ovulation also occurs in the estrous cycle of other female mammals, which differs in many fundamental ways from the menstrual cycle...
has occurred. In postmenarchal girls, about 80% of the cycles were anovulatory in the first year after menarche, 50% in the third and 10% in the sixth year. 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
Anthropology
Anthropology is the study of humanity. It has origins in the humanities, the natural sciences, and the social sciences. The term "anthropology" is from the Greek anthrōpos , "man", understood to mean mankind or humanity, and -logia , "discourse" or "study", and was first used in 1501 by German...
term for this state of potential fertility is nubility.
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
Sexual intercourse
Sexual intercourse, also known as copulation or coitus, commonly refers to the act in which a male's penis enters a female's vagina for the purposes of sexual pleasure or reproduction. The entities may be of opposite sexes, or they may be hermaphroditic, as is the case with snails...
shortly before her menarche to conceive and become pregnant
Pregnancy
Pregnancy refers to the fertilization and development of one or more offspring, known as a fetus or embryo, in a woman's uterus. In a pregnancy, there can be multiple gestations, as in the case of twins or triplets...
, which would delay her menarche until after the birth. This goes against the widely held assumption that a woman cannot become pregnant until after menarche.
Onset
When menarche occurs, it confirms that the girl has had a gradual estrogenEstrogen
Estrogens , oestrogens , or œstrogens, are a group of compounds named for their importance in the estrous cycle of humans and other animals. They are the primary female sex hormones. Natural estrogens are steroid hormones, while some synthetic ones are non-steroidal...
-induced growth of the uterus
Uterus
The uterus or womb is a major female hormone-responsive reproductive sex organ of most mammals including humans. One end, the cervix, opens into the vagina, while the other is connected to one or both fallopian tubes, depending on the species...
, especially the endometrium
Endometrium
-Function:The endometrium is the innermost glandular layer and functions as a lining for the uterus, preventing adhesions between the opposed walls of the myometrium, thereby maintaining the patency of the uterine cavity. During the menstrual cycle or estrous cycle, the endometrium grows to a...
, and that the "outflow tract" from the uterus, through the cervix
Cervix
The cervix is the lower, narrow portion of the uterus where it joins with the top end of the vagina. It is cylindrical or conical in shape and protrudes through the upper anterior vaginal wall...
to the vagina
Vagina
The vagina is a fibromuscular tubular tract leading from the uterus to the exterior of the body in female placental mammals and marsupials, or to the cloaca in female birds, monotremes, and some reptiles. Female insects and other invertebrates also have a vagina, which is the terminal part of the...
, is open.
In very rare instances, menarche may occur at an unusually early age, preceding thelarche
Thelarche
Thelarche is the onset of secondary breast development, usually occurring at the beginning of puberty in girls. Its etymology is from Greek θηλή [tʰelḗ], “nipple” and ἀρχή [arkʰḗ], “beginning, onset”. Thelarche is usually noticed as a firm, tender lump directly under the centre of the nipple...
and other signs of puberty. This is termed isolated premature menarche, but other causes of bleeding must be investigated and excluded. Growth is usually normal. Isolated premature menarche is rarely the first manifestation of precocious puberty
Precocious puberty
As a medical term, precocious puberty describes puberty occurring at an unusually early age. In most of these children, the process is normal in every respect except the unusually early age, and simply represents a variation of normal development. In a minority of children, the early development is...
.
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.
Effects of stress and social environment
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 physiological 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:
- The increased incidence of childhood obesityChildhood obesityChildhood obesity is a condition where excess body fat negatively affects a child's health or wellbeing. As methods to determine body fat directly are difficult, the diagnosis of obesity is often based on BMI. Due to the rising prevalence of obesity in children and its many adverse health effects...
(both estrogen and progesterone molecules are derived from cholesterol). - Absence of father from the home from early childhood
- High-conflict family relationships
- Had a low birthweight
- Are singletons
- Are non-white
- Experienced pre-eclampsia in the womb
- Were exposed to smoking
- Were not breast-fed
- Lacked exercise in childhood
Some of the aspects of family structure and function reported to be independently associated with later menarche:
- Larger family size
- Warmer, closer or more positive relationship with biological father
- Warmer, more supportive, low-stress family environment
- Have a number of older siblings
Other research has focused on the effect of childhood stress
Stress (medicine)
Stress is a term in psychology and biology, borrowed from physics and engineering and first used in the biological context in the 1930s, which has in more recent decades become commonly used in popular parlance...
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
Life history theory
Life history theory posits that the schedule and duration of key events in an organism's lifetime are shaped by natural selection to produce the largest possible number of surviving offspring...
and demonstrated in many other mammals.
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 pheromonePheromoneA pheromone is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting outside the body of the secreting individual to impact the behavior of the receiving individual...
s, have been suggested based on animal research. - Most of these "effects" are statistical associations revealed by epidemiologicEpidemiologyEpidemiology is the study of health-event, health-characteristic, or health-determinant patterns in a population. It is the cornerstone method of public health research, and helps inform policy decisions and evidence-based medicine by identifying risk factors for disease and targets for preventive...
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.
Changes in time of average age
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. A decline in the average age of menarche from 17 to 13 in Europe from 1850 to 1960 is well documented, but a large North American survey reported only a 2-3 month decline from the mid-1970s to the mid-1990s. A 2011 study found that each 1 kg/m2 increase in childhood body-mass index (BMI) can be expected to result in a 6.5% higher absolute risk of early menarche (before age 12 years). The decline 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 estrogen or the urbanization and 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 much 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 slightly earlier than the white girls at 25%.
Culture
Menarche is celebrated in many cultures around the world as a rite of passageRite of passage
A rite of passage is a ritual event that marks a person's progress from one status to another. It is a universal phenomenon which can show anthropologists what social hierarchies, values and beliefs are important in specific cultures....
, a time to recognize that a girl is moving into womanhood.
Rites of passage
Some cultures have in past centuries had rites of passage for a girl experiencing menarche.Africa
- In the Tiv ethnic group in NigeriaNigeriaNigeria , officially the Federal Republic of Nigeria, is a federal constitutional republic comprising 36 states and its Federal Capital Territory, Abuja. The country is located in West Africa and shares land borders with the Republic of Benin in the west, Chad and Cameroon in the east, and Niger in...
, four lines are cut in the girl's abdomen, the practice of which is thought to make her a woman and more fertile.
Asia, Australia, and Pacific Islands
- In Australia, the AboriginesIndigenous AustraliansIndigenous Australians are the original inhabitants of the Australian continent and nearby islands. The Aboriginal Indigenous Australians migrated from the Indian continent around 75,000 to 100,000 years ago....
treat a girl to "love magic." The women teach her of the female powers and the physical changes marking womanhood.
- When a Japanese girl has her first period, the family celebrates by eating red-colored rice and beans (sekihanSekihanSekihan , literally red rice, is a Japanese traditional dish. It is sticky rice steamed with azuki beans, which give a reddish color to the rice, hence its name....
).
- The Ulithi (oo-lith-ee) tribe of MicronesiaMicronesiaMicronesia is a subregion of Oceania, comprising thousands of small islands in the western Pacific Ocean. It is distinct from Melanesia to the south, and Polynesia to the east. The Philippines lie to the west, and Indonesia to the southwest....
call a girl's menarche kufar (koo-faar); She goes to a menstrual house, where the women bathe her and recite spells. The girl then returns to the menstrual house when her next period comes.
- Some Sri LankaSri LankaSri Lanka, officially the Democratic Socialist Republic of Sri Lanka is a country off the southern coast of the Indian subcontinent. Known until 1972 as Ceylon , Sri Lanka is an island surrounded by the Indian Ocean, the Gulf of Mannar and the Palk Strait, and lies in the vicinity of India and the...
ns note the time and day of menarche. An astrologerAstrologerAn astrologer practices one or more forms of astrology. Typically an astrologer draws a horoscope for the time of an event, such as a person's birth, and interprets celestial points and their placements at the time of the event to better understand someone, determine the auspiciousness of an...
is contacted, who studies the star's alignment at the noted moment, in order to predict the girl's future. Her house is prepared for a ritual bathing, where the girl is scrubbed all over her body by the women of the family; she is then dressed in white. Her family invites relatives and close friends for a ceremony to celebrate the new young woman, during which the girl may receive special gifts and money.
- In some remote parts of India, a tribal girl who has reached puberty is given a ceremonial bath, decked with ornate jewels and garments, and the girl's kith and kin are all invited for a ceremony, in which it is announced that the girl has come of age and that celebrations follow.
- In some Indian communities, young women are given a special menarche ceremony called Ruthu Sadangu.
- In Nepal, KumariKumariKumari, or Kumari Devi, is the tradition of worshipping young pre-pubescent girls as manifestations of the divine female energy or devi in Hindu religious traditions. Kumari means young unmarried girl. Kumari word is derived from Sanskrit word Kaumarya meaning "virgin". In Nepali and some Indian...
s are young girls worshiped as goddesses by Hindus and some Buddhists, at the onset of menarche it is believed the goddess spirit vacates her body and they are returned to ordinary life after a series of rituals.
North America
- The NavajoNavajo peopleThe Navajo of the Southwestern United States are the largest single federally recognized tribe of the United States of America. The Navajo Nation has 300,048 enrolled tribal members. The Navajo Nation constitutes an independent governmental body which manages the Navajo Indian reservation in the...
Indians have a celebration called kinaalda (kinn-all-duh). Girls run footraces to show strength. A cornmeal pudding is made for the tribe to taste. The girls who experience menarche wear special clothes and style their hair like the Navajo goddess "Changing Woman."
- The Nootka Indians believe menarche to be a time for a physical strength test; the girl is taken out to sea and left alone. She is to swim back and is cheered upon returning to the shore of the village.
- The MescaleroMescaleroMescalero is an Apache tribe of Southern Athabaskan Native Americans. The tribe is federally recognized as the Mescalero Apache Tribe of the Mescalero Apache Reservation in southcentral New Mexico...
Apaches consider their menarche celebration the most important. Each year, an 8-day-long ceremony is celebrated in honor of each girl who began her period earlier that year. The first four days include feasting and dancing. Boy singers recount the history of the tribe each evening. The other four days are a private celebration during which girls have a private ceremony, reflecting on their passing into womanhood.
See also
- AdrenarcheAdrenarcheAdrenarche is an early sexual maturation stage in some higher primates that in humans typically occurs at around 6 to 8 years of age. During adrenarche the adrenal cortex secretes increased levels of androgens such as DHEA and DHEAS, but without increased cortisol levels. Adrenarche is the result...
- Delayed pubertyDelayed pubertyPuberty is described as delayed puberty with exceptions when an organism has passed the usual age of onset of puberty with no physical or hormonal signs that it is beginning. Puberty may be delayed for several years and still occur normally, in which case it is considered constitutional delay, a...
- GonadarcheGonadarcheGonadarche refers to the earliest gonadal changes of puberty. In response to pituitary gonadotropins, the ovaries in girls and the testes in boys begin to grow and increase the production of the sex steroids, especially estradiol and testosterone....
- Lina MedinaLina MedinaLina Medina is the youngest confirmed mother in medical history, giving birth at the age of five years, seven months and 17 days...
, who had her menarche at age 8 months and is the youngest mother in history - MenopauseMenopauseMenopause is a term used to describe the permanent cessation of the primary functions of the human ovaries: the ripening and release of ova and the release of hormones that cause both the creation of the uterine lining and the subsequent shedding of the uterine lining...
, the equivalent opposite change at the end of the child-bearing years - Menstrual cycleMenstrual cycleThe menstrual cycle is the scientific term for the physiological changes that can occur in fertile women for the purpose of sexual reproduction. This article focuses on the human menstrual cycle....
- PubarchePubarchePubarche refers to the first appearance of pubic hair in a child. Pubarche is one of the physical changes of puberty but should not be equated with it since it may occur independently of complete puberty...
- PubertyPubertyPuberty is the process of physical changes by which a child's body matures into an adult body capable of reproduction, as initiated by hormonal signals from the brain to the gonads; the ovaries in a girl, the testes in a boy...
, for a more detailed discussion of factors affecting timing - SpermarcheSpermarcheThe first ejaculatory experience of boys is termed semenarche.Spermarche refers to the beginning of development of sperm in boys' testicles at puberty. It contrasts with menarche in girls. Depending on their upbringing, cultural differences, and prior sexual knowledge, boys may have different...
- ThelarcheThelarcheThelarche is the onset of secondary breast development, usually occurring at the beginning of puberty in girls. Its etymology is from Greek θηλή [tʰelḗ], “nipple” and ἀρχή [arkʰḗ], “beginning, onset”. Thelarche is usually noticed as a firm, tender lump directly under the centre of the nipple...
External links
- Better Than Sex Ed: "My First Period"
- http://www.livescience.com/humanbiology/060713_menarche_onset.html Discusses some of the social influences