Editing Stretch marks (section)

== Causes ==
Stretch marks appear to be caused by stretching of the skin. This is especially true when there is an increase in [[cortisone]]<ref name=":0">{{cite web|url=http://www.mayoclinic.org/diseases-conditions/stretch-marks/basics/causes/con-20032624|title=Stretch marks - Symptoms and causes|website=mayoclinic.org|access-date=4 April 2018|archive-date=9 December 2015|archive-url=https://web.archive.org/web/20151209032515/http://www.mayoclinic.org/diseases-conditions/stretch-marks/basics/causes/con-20032624|url-status=live}}</ref>{{snd}} an increase in cortisone levels can increase the probability or severity of stretch marks by reducing the skin's pliability. More specifically, it affects the [[dermis]] by preventing the [[fibroblast]]s from forming [[collagen]] and [[elastin]] fibers necessary to keep rapidly growing skin taut; this can create a lack of supportive material as the skin is stretched, and lead to dermal and [[epidermis|epidermal]] tearing, which in turn can produce scarring in the form of stretch marks. This is particularly the case when there is new tissue growth, which can interfere with the underlying physical support of the dermis or epidermis by displacing the supportive tissue.{{cn|date=September 2021}}

Examples of cases where stretch marks are common include weight gain (in the form of [[fat]] and/or [[muscle]]), [[pregnancy]], and adolescent [[growth spurt]]s, though it is also noted that some medications, as well as other medical conditions and diseases, may increase the likelihood of stretch marks appearing. Common medications that can contribute to stretch marks include "[[corticosteroid]] creams, lotions and pills and chronic use of oral or systemic [[steroid]]s".<ref name=":0" /> Medical conditions that can contribute to stretch marks include [[Ehlers–Danlos syndrome]], [[Cushing's syndrome]], [[Marfan syndrome]], and [[Adrenal gland disorder|adrenal gland diseases]].<ref>{{cite web |vauthors=Burrows N |title=Skin |url=https://www.ehlers-danlos.org/what-is-eds/information-on-eds/skin/ |website=Ehlers-Danlos Support UK |access-date=14 June 2023 |archive-date=14 June 2023 |archive-url=https://web.archive.org/web/20230614095545/https://www.ehlers-danlos.org/what-is-eds/information-on-eds/skin/ |url-status=live }}</ref><ref>{{cite web |title=Cushing Disease |url=https://medlineplus.gov/genetics/condition/cushing-disease/ |website=Medline Plus |access-date=14 June 2023 |archive-date=14 June 2023 |archive-url=https://web.archive.org/web/20230614100749/https://medlineplus.gov/genetics/condition/cushing-disease/ |url-status=live }}</ref><ref>{{cite web |title=Symptoms - Marfan syndrome |url=https://www.nhs.uk/conditions/marfan-syndrome/symptoms/ |website=National Health Service |date=3 October 2018 |access-date=14 June 2023 |archive-date=14 June 2023 |archive-url=https://web.archive.org/web/20230614100748/https://www.nhs.uk/conditions/marfan-syndrome/symptoms/ |url-status=live }}</ref>

[[Asian people|Asians]] are more prone to stretch marks.<ref>{{cite web|url=https://www.newsobserver.com/living/article10345682.html|title=}}</ref>

===Pregnancy===
[[File:Squircle belly (19004951).jpg|Striae gravidarum in a pregnant woman at 38 weeks|thumb]]

Pregnancy stretch marks, also known as ''striae gravidarum'', are a specific form of [[scarring]] of the skin of the abdominal area due to rapid expansion of the [[uterus]] as well as sudden weight gain during pregnancy. About 90% of pregnant women are affected.<ref name=BJD2015>{{cite journal | vauthors = Korgavkar K, Wang F | title = Stretch marks during pregnancy: a review of topical prevention | journal = The British Journal of Dermatology | volume = 172 | issue = 3 | pages = 606–615 | date = March 2015 | pmid = 25255817 | doi = 10.1111/bjd.13426 | hdl-access = free | s2cid = 23269984 | hdl = 2027.42/110856 }}</ref>

A number of additional factors appear to promote the appearance of stretch marks: one study of 324 women, done just after they had given birth, demonstrated that low maternal age, high [[body mass index]], weight gain over 15&nbsp;kg (33 pounds) and higher neonatal birth weight were independently correlated with the occurrence of striae. Teenagers were found to be at the highest risk of developing severe striae.<ref name="Striae gravidarum in primiparae">{{cite journal | vauthors = Atwal GS, Manku LK, Griffiths CE, Polson DW | title = Striae gravidarum in primiparae | journal = The British Journal of Dermatology | volume = 155 | issue = 5 | pages = 965–969 | date = November 2006 | pmid = 17034526 | doi = 10.1111/j.1365-2133.2006.07427.x | s2cid = 42623629 | author-link3 = Chris Griffiths (dermatologist) }}</ref>

These skin marks are [[Signs and symptoms of pregnancy|symptoms of pregnancy]] caused by the tearing of the [[dermis]], resulting in [[atrophy]] and loss of [[Rete pegs|rete ridges]].<ref>{{cite journal | vauthors = Kroumpouzos G, Cohen LM | title = Specific dermatoses of pregnancy: an evidence-based systematic review | journal = American Journal of Obstetrics and Gynecology | volume = 188 | issue = 4 | pages = 1083–1092 | date = April 2003 | pmid = 12712115 | doi = 10.1067/mob.2003.129 | doi-access = free }}</ref> These scars often appear as reddish or bluish streaks on the abdomen, and can also appear on the breasts and thighs. Some of these striae disappear with time, while others remain as permanent discolorations of the body.{{Citation needed|date=July 2024}}

Mechanical distension and rapidly developing areas of the body during pregnancy (such as the abdomen, breasts, and thighs) are most commonly associated with striae formation. Some have suggested that [[relaxin]] and [[estrogen]] combined with higher levels of [[cortisol]] during pregnancy can cause an accumulation of [[mucopolysaccharide]]s, which increases water absorption of [[connective tissue]], making it prime for tearing under mechanical [[Stress (mechanics)|stress]].<ref name="ReferenceA"/><ref name="Striae gravidarum in primiparae"/> There also seems to be an association between higher body mass indices and in women with bigger babies and the incidence and severity of striae. Also, younger women seem to be at higher risk of developing striae during pregnancy.<ref name="ReferenceA"/><ref name="ReferenceB">{{cite journal | vauthors = Thomas RG, Liston WA | title = Clinical associations of striae gravidarum | journal = Journal of Obstetrics and Gynaecology | volume = 24 | issue = 3 | pages = 270–271 | date = April 2004 | pmid = 15203623 | doi = 10.1080/014436104101001660779 | s2cid = 36643446 }}</ref>

The prevalence and severity of striae gravidarum varies among populations. The current literature suggest that in the general population of the United States, there is a 50% to 90% prevalence of striae associated with pregnancy,<ref name="ReferenceB"/> partly as a result of the normal hormonal changes associated with pregnancy and partly due to stretching of skin fibers.<ref name=CC-Brennan-2012>{{cite journal | vauthors = Brennan M, Young G, Devane D | title = Topical preparations for preventing stretch marks in pregnancy | journal = The Cochrane Database of Systematic Reviews | volume = 2012 | issue = 11 | pages = CD000066 | date = November 2012 | pmid = 23152199 | pmc = 10001689 | doi = 10.1002/14651858.CD000066.pub2 }}</ref><ref name=Tunzi-2007>{{cite journal | vauthors = Tunzi M, Gray GR | title = Common skin conditions during pregnancy | journal = American Family Physician | volume = 75 | issue = 2 | pages = 211–218 | date = January 2007 | pmid = 17263216 }}</ref> Many women experience striae gravidarum during their first pregnancy. Nearly 45% percent of women develop striae gravidarum before 24 weeks of gestation.{{Citation needed|date=July 2024}} Many women who develop lesions during the first pregnancy do not develop them during later pregnancies. Genetic factors such as [[genealogy]] and race also seem to be predictive in the appearance of striae.<ref name="Tunzi-2007" />