Menarhă

Menarha (limba greacă: μήν mēn „lună” + ἀρχή arkhē „început”) este primul ciclu menstrual sau prima menstruație la fete. Atât din perspectivă socială cât și din cea medicală, este adesea considerat drept evenimentul central al pubertății feminine, deoarece semnifică posibilitatea de a rămâne gravidă.

Fetele experimentează menarha la vârste diferite. Momentul acesteia este influențat de biologia feminină, de asemenea de factori genetici și de mediu, în special nutriționali. Vârsta media a menarhei a scăzut în ultimul secol, dar mărimea acestei scăderi și factorii care au produs-o rămân subiecte de dezbatere. Vârsta medie la nivel mondial este dificil de estimat precis, variind semnificativ din punct de vedere geografic, rasial, etnic și după alte caracteristici. Variate estimări au stabilit-o la 13 ani.^[1] Există o vârsta mai ridicată a menarhei în populații asiatice comparativ cu cele occidentale.^[2] Vârsta medie a menarhei este de circa 12,5 ani în SUA,^[3] 12,7 în Canada,^[4] și 12,9 în Marea Britanie.^[5] Un studiu asupra unor fete din Istanbul, Turcia, a găsit vârsta mediană de 12,7 ani.^[6]

Vârsta medie a primei menstruații a scăzut treptat în ultimii 100 ani.^[7]

Vezi și modificare

Adrenarhă
Pubertate întârziată
Gonadarhă
Lina Medina, care a avut menarha la vârsta de 8 luni și a fost cea mai tânără mamă din istorie
Menopauză, echivalentul schimbării de sens opus la sfârșitul vârstei fertile
Pubarhă
Spermarhă
Telarhă

Note modificare

^ Shawky, S.; Milaat, W. (2000). „Early teenage marriage and subsequent pregnancy outcome” (PDF). Eastern Mediterranean Health Journal. 6 (1): 46–54. PMID 11370340.
^ „Risk Factors for Breast Cancer in India: an INDOX Case-Control Study”. INDOX Cancer Research Network. Arhivat din original la 2 martie 2013. Accesat în 20 mai 2013.
^ Anderson SE, Dallal GE, Must A (aprilie 2003). „Relative weight and race influence average age at menarche: results from two nationally representative surveys of US girls studied 25 years apart”. Pediatrics. 111 (4 Pt 1): 844–50. doi:10.1542/peds.111.4.844. PMID 12671122.
^ Al-Sahab B, Ardern CI, Hamadeh MJ, Tamim H (noiembrie 2010). „Age at menarche in Canada: results from the National Longitudinal Survey of Children & Youth”. BMC Public Health. 10: 736. doi:10.1186/1471-2458-10-736. PMC 3001737  . PMID 21110899.
^ Hamilton-Fairley, Diana (2004). Obstetrics and Gynaecology (PDF) (ed. 2nd). Blackwell. p. 29. ISBN 978-1-4051-2066-1. Arhivat din original (PDF) la 9 octombrie 2018. Accesat în 9 noiembrie 2013.
^ Atay Z, Turan S, Guran T, Furman A, Bereket A (iulie 2011). „Puberty and influencing factors in schoolgirls living in Istanbul: end of the secular trend?”. Pediatrics. 128 (1): e40–5. doi:10.1542/peds.2010-2267. PMID 21669888.
^
- Strickland, Bonnie B., ed. (2001). „Puberty”. The Gale Encyclopedia of Psychology (ed. Second). Gale Group. p. 528. ISBN 978-0-7876-4786-5. 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).
- Steinberg, Laurence (2000). „Adolescence”. În Strickland, Bonnie B. The Gale Encyclopedia of Psychology (ed. Second). Gale Group. p. 11. 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.

[1] Shawky, S.; Milaat, W. (2000). „Early teenage marriage and subsequent pregnancy outcome” (PDF). Eastern Mediterranean Health Journal. 6 (1): 46–54. PMID 11370340.

[2] „Risk Factors for Breast Cancer in India: an INDOX Case-Control Study”. INDOX Cancer Research Network. Arhivat din original la 2 martie 2013. Accesat în 20 mai 2013.

[AndersonEtAl2003-3] Anderson SE, Dallal GE, Must A (aprilie 2003). „Relative weight and race influence average age at menarche: results from two nationally representative surveys of US girls studied 25 years apart”. Pediatrics. 111 (4 Pt 1): 844–50. doi:10.1542/peds.111.4.844. PMID 12671122.

[4] Al-Sahab B, Ardern CI, Hamadeh MJ, Tamim H (noiembrie 2010). „Age at menarche in Canada: results from the National Longitudinal Survey of Children & Youth”. BMC Public Health. 10: 736. doi:10.1186/1471-2458-10-736. PMC 3001737  . PMID 21110899.

[5] Hamilton-Fairley, Diana (2004). Obstetrics and Gynaecology (PDF) (ed. 2nd). Blackwell. p. 29. ISBN 978-1-4051-2066-1. Arhivat din original (PDF) la 9 octombrie 2018. Accesat în 9 noiembrie 2013.

[pmid21669888-6] Atay Z, Turan S, Guran T, Furman A, Bereket A (iulie 2011). „Puberty and influencing factors in schoolgirls living in Istanbul: end of the secular trend?”. Pediatrics. 128 (1): e40–5. doi:10.1542/peds.2010-2267. PMID 21669888.

[Strickland2001-7] 
Strickland, Bonnie B., ed. (2001). „Puberty”. The Gale Encyclopedia of Psychology (ed. Second). Gale Group. p. 528. ISBN 978-0-7876-4786-5. 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).

Steinberg, Laurence (2000). „Adolescence”. În Strickland, Bonnie B. The Gale Encyclopedia of Psychology (ed. Second). Gale Group. p. 11. 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.

[8] Strickland, Bonnie B., ed. (2001). „Puberty”. The Gale Encyclopedia of Psychology (ed. Second). Gale Group. p. 528. ISBN 978-0-7876-4786-5. 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).

[9] Steinberg, Laurence (2000). „Adolescence”. În Strickland, Bonnie B. The Gale Encyclopedia of Psychology (ed. Second). Gale Group. p. 11. 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.

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