Editing Delayed puberty (section)

==Timing and definitions==

Puberty is considered delayed when the child has not begun puberty when two [[standard deviation]]s or about 95% of children from similar backgrounds have.<ref name=":0" /><ref name=":4" /><ref>{{cite journal | vauthors = Traggiai C, Stanhope R | title = Disorders of pubertal development | journal = Best Practice & Research. Clinical Obstetrics & Gynaecology | volume = 17 | issue = 1 | pages = 41–56 | date = February 2003 | pmid = 12758225 | doi = 10.1053/ybeog.2003.0360 }}</ref>

In North American girls, puberty is considered delayed when breast development has not begun by age 13, when they have not started menstruating by age 15,<ref name=":1" /> and when there is no increased growth rate.<ref name=":4" />  Furthermore, slowed progression through the [[Tanner scale]] or lack of [[menarche]] within 3 years of breast development may also be considered delayed puberty.<ref name=":4" />

In the United States, the age of onset of puberty in girls depends heavily on their racial background. Delayed puberty means the lack of breast development by age 12.8 years for White girls, and by age 12.4 years for Black girls.<ref name=":0" /><ref name=":4" /> The lack of menstruation by age 15 in any ethnic background is considered delayed.<ref name=":4" />

In North American boys, puberty is considered delayed when the testes remain less than 2.5&nbsp;cm in diameter<ref name=":1" /> or less than 4 mL in volume by the age of 14.<ref name=":11" /> Delayed puberty is more common in males.<ref name=":1" />

Although the absence of pubic and/or axillary hair is common in children with delayed puberty, the presence of sexual hair is due to adrenal sex hormone secretion unrelated to the sex hormones produced by the ovaries or testes.<ref name=":7">{{cite journal|vauthors=Dunkel L, Quinton R|date=June 2014|title=Transition in endocrinology: induction of puberty|journal=European Journal of Endocrinology|language=en-US|volume=170|issue=6|pages=R229–39|doi=10.1530/EJE-13-0894|pmid=24836550|doi-access=free}}</ref><ref name=":4" />

The age of onset of puberty is dependent on genetics, general health, socioeconomic status, and environmental exposures. Children residing closer to the equator, at lower altitudes, in cities and other urban areas generally begin the process of puberty earlier than their counterparts.<ref name=":0" /> Mildly obese to morbidly obese children are also more likely to begin puberty earlier than children of normal weight.<ref name=":13" /> Variations in genes related to obesity, such as FTO or NEGRI, have been associated with earlier onset of puberty.<ref name=":0" /> Children whose parents started puberty at an earlier age were also more likely to experience it themselves, especially in women where onset of menstruation correlated well between mothers and daughters and between sisters.<ref name=":0" />