乳房初长

乳房初长（Thelarche）是指乳房的第二次发育^[1]，一般是出现在女性青春期的初期。乳房初长一开始会出现在乳头及乳晕中心的下方，是一个小而紧实的隆起物。乳房初长也会称为“胸蕾”（breast bud），对应谭纳标准阶段二的乳房发育（谭纳标准的阶段一是乳房维持在青春期前未发育的情形）。乳房初长可能会出现在单侧的乳房，也可能两侧乳房同时出现。

乳房初长是60%的女性在进入青春期时，第一个出现的身体变化，一般是在八岁以后，原因是因为雌二醇浓度的提高。女性的两侧乳房不一样大是很正常的，尤其在乳房发育期间也容易出现。根据统计数据来看，比较常出现左侧乳房大一点点的情形^[2]。极少数的情形下，两侧乳房的大小会有明显的差异，甚至一个乳房完全没有发育。

虽然有些男性的青春期也会有乳房发育的的情形，不过这称为男性乳房发育症，多半也不会用“乳房初长”来描述男性乳房的发育。

若乳房初长太早出现，这可能是真性早熟症（英语：precocious puberty）的第一个表征。不过若没有伴随其他青春期或是性激素的变化，算是乳房早熟（英语：premature thelarche），一般不需特别进行治疗。

乳房初长变异

乳房初长变异是介于乳房早熟症及性早熟症之间的情形^[3]^[4]。^[3]。乳房初长变异一般会伴随阴毛的发育（阴毛初现）以及骨骼的成长，不过乳房初长变异不像性早熟症，这些发育不意味著性发育的成熟^[3]^[5]。

乳房初长的种族差异

乳房初长的平均年龄也会随种族而不同^[6]^[7]^[8]。美国非裔女性的乳房初长年龄约在8.9至9.5岁、高加索裔约在10-10.4岁、西班牙裔约在9.8岁^[6]^[7]。

参考文献

^
Dictionary.com > thelarche （页面存档备份，存于互联网档案馆） Citing:
- The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995
- Merriam-Webster's Medical Dictionary, © 2007
^ C.W. Loughry; et al. Breast volume measurement of 598 women using biostereometric analysis. Annals of Plastic Surgery. 1989, 22 (5): 380–385. PMID 2729845. doi:10.1097/00000637-198905000-00002.
^ ^3.0 ^3.1 ^3.2 Sultan, Charles. Pediatric and Adolescent Gynecology: Evidence-based Clinical Practice. Karger Medical and Scientific Publishers. 2004-01-01. ISBN 9783805576239.
^ Sultan, C. Pediatric and Adolescent Gynecology. Karger Medical and Scientific Publishers. 2012-07-30. ISBN 9783805593373.
^ Balen, Adam H.; Creighton, Sarah M.; Davies, Melanie C.; MacDougall, Jane; Stanhope, Richard. Paediatric and Adolescent Gynaecology: A Multidisciplinary Approach. Cambridge University Press. 2004-04-01. ISBN 9781107320185.
^ ^6.0 ^6.1 Colvin, Caroline Wingo; Abdullatif, Hussein. Anatomy of female puberty: The clinical relevance of developmental changes in the reproductive system. Clinical Anatomy. 2012-09-19, 26 (1): 115–129. ISSN 0897-3806. doi:10.1002/ca.22164.
^ ^7.0 ^7.1 Sanfilippo, Joseph S.; Lara-Torre, Eduardo; Edmonds, D. Keith; Templeman, Claire (编). Clinical Pediatric and Adolescent Gynecology. ISBN 9780203091784. OCLC 992561838.
^ Bauer, Andrew J.; Francis, Gary L.; Poth, Merrily. Review of Precocious Puberty: Part III—Premature Thelarche and Premature Adrenarche. Variations of Normal?. The Endocrinologist. May 2001, 11 (3): 196–203. ISSN 1051-2144. doi:10.1097/00019616-200105000-00006.

Isolated Premature Thelarche （页面存档备份，存于互联网档案馆）

外部链接

青春期资讯

卫生福利部国民健康署-健康九九网站-青春好漾馆（页面存档备份，存于互联网档案馆）
香港特别行政区政府卫生署学生健康服务-性教育（页面存档备份，存于互联网档案馆）

[1] Dictionary.com > thelarche （页面存档备份，存于互联网档案馆） Citing:
The American Heritage® Stedman's Medical Dictionary
Copyright © 2002, 2001, 1995
Merriam-Webster's Medical Dictionary, © 2007

[2] The American Heritage® Stedman's Medical Dictionary

[3] Merriam-Webster's Medical Dictionary, © 2007

[asymmetry-2] C.W. Loughry; et al. Breast volume measurement of 598 women using biostereometric analysis. Annals of Plastic Surgery. 1989, 22 (5): 380–385. PMID 2729845. doi:10.1097/00000637-198905000-00002.

[:7-3] 3.0 ^3.1 ^3.2 Sultan, Charles. Pediatric and Adolescent Gynecology: Evidence-based Clinical Practice. Karger Medical and Scientific Publishers. 2004-01-01. ISBN 9783805576239.

[4] Sultan, C. Pediatric and Adolescent Gynecology. Karger Medical and Scientific Publishers. 2012-07-30. ISBN 9783805593373.

[:8-5] Balen, Adam H.; Creighton, Sarah M.; Davies, Melanie C.; MacDougall, Jane; Stanhope, Richard. Paediatric and Adolescent Gynaecology: A Multidisciplinary Approach. Cambridge University Press. 2004-04-01. ISBN 9781107320185.

[:3-6] 6.0 ^6.1 Colvin, Caroline Wingo; Abdullatif, Hussein. Anatomy of female puberty: The clinical relevance of developmental changes in the reproductive system. Clinical Anatomy. 2012-09-19, 26 (1): 115–129. ISSN 0897-3806. doi:10.1002/ca.22164.

[:5-7] 7.0 ^7.1 Sanfilippo, Joseph S.; Lara-Torre, Eduardo; Edmonds, D. Keith; Templeman, Claire (编). Clinical Pediatric and Adolescent Gynecology. ISBN 9780203091784. OCLC 992561838.

[:4-8] Bauer, Andrew J.; Francis, Gary L.; Poth, Merrily. Review of Precocious Puberty: Part III—Premature Thelarche and Premature Adrenarche. Variations of Normal?. The Endocrinologist. May 2001, 11 (3): 196–203. ISSN 1051-2144. doi:10.1097/00019616-200105000-00006.

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