Thelarche, also known as breast budding, is the onset of secondary breast development, often representing the beginning of pubertal development.[1] It is the stage at which male and female breasts differentiate due to variance in hormone levels; however, some males have a condition in which they develop breasts, termed gynecomastia.[2][3] Thelarche typically occurs between the ages of 8 and 13 years with significant variation between individuals.[4][5][1] However, the initial growth of breast tissue occurs during fetal development.
Usually, females experience menarche about two years after thelarche has begun, with complete breast development from thelarche to adult breasts, taking between 2 and 4 years but can be up to 18.[1][6] Moreover, puberty is considered delayed if breast development does not start at age 13 or if a female has not had her first period (menarche) within three years of thelarche.[7] Additionally, secondary breast development occurring before the age of 7 years could be a sign of premature thelarche or precocious puberty. Of note, for some girls, thelarche will occur, with subsequent regression of breast development, and then months or years later, normal breast growth will commence again accompanied by normal pubertal changes; this is termed transient thelarche.[1]
Pubertal changes, including breast development, are assessed using the Tanner Scale (Sexual Maturity Rating Scale) where stage 1 is before, stage 2 is the breast budding or thelarche stage, stages 3 and 4 are continual breast growth and areolar development, and stage 5 signifies completion of development.[6][8] This system does not use breast size but instead examines the shape of breasts, nipples, and areolae to determine the progression of growth.[6]
Various hormones interact and result in the changes seen during thelarche. The growth and accumulation of adipose tissue in the breasts are induced by estrogen, while the development of mammary glands and areolae are caused by progesterone; both estrogen and progesterone are produced by ovaries.[1][3][6] Due to change in hormone levels, young breasts are likely to develop asymmetrically, and in many cases, adult breasts will remain unequal in size or shape.[4][6]
- ^ a b c d e De Silva, Nirupama K. (April 2018). "Breast development and disorders in the adolescent female". Best Practice & Research Clinical Obstetrics & Gynaecology. 48: 40–50. doi:10.1016/j.bpobgyn.2017.08.009. ISSN 1521-6934. PMID 28935365.
- ^ Bao, Yong; Diamantopoulos, Stavros (2007-09-01). "Gynecomastia and Premature Thelarche: A Guide for Practitioners". Pediatrics in Review. 28 (9): e57–e68. doi:10.1542/pir.28-9-e57. ISSN 0191-9601. PMID 17766590.
- ^ a b Colvin, Caroline Wingo; Abdullatif, Hussein (2012-09-19). "Anatomy of female puberty: The clinical relevance of developmental changes in the reproductive system". Clinical Anatomy. 26 (1): 115–129. doi:10.1002/ca.22164. ISSN 0897-3806. PMID 22996962. S2CID 46057971.
- ^ a b Bauer, Andrew J.; Francis, Gary L.; Poth, Merrily (May 2001). "Review of Precocious Puberty: Part III—Premature Thelarche and Premature Adrenarche. Variations of Normal?". The Endocrinologist. 11 (3): 196–203. doi:10.1097/00019616-200105000-00006. ISSN 1051-2144.
- ^ Sanfilippo, Joseph S.; Lara-Torre, Eduardo; Edmonds, D. Keith; Templeman, Claire, eds. (2008-12-24). Clinical Pediatric and Adolescent Gynecology. CRC Press. ISBN 9780203091784. OCLC 992561838.
- ^ a b c d e Litt, Iris F. (1997). Taking Our Pulse: The Health of America's Women. Stanford University Press. p. 9. ISBN 9780804731379.
breast development stages.
- ^ Sultan, Charles; Gaspari, Laura; Maimoun, Laurent; Kalfa, Nicolas; Paris, Françoise (April 2018). "Disorders of puberty" (PDF). Best Practice & Research Clinical Obstetrics & Gynaecology. 48: 62–89. doi:10.1016/j.bpobgyn.2017.11.004. PMID 29422239.
- ^ Hauspie, Roland C.; Cameron, Noël; Molinari, Luciano (2004-06-24). Methods in Human Growth Research. Cambridge University Press. ISBN 9781139451680.