Worldwide Secular Trends in Age at Pubertal Onset Assessed by Breast Development Among Girls

Abstract

IMPORTANCEThe initial clinical sign of pubertal onset in girls is breast gland development (thelarche). Although numerous studies have used recalled age at menarche (first menstruation) to assess secular trends of pubertal timing, no systematic review has been conducted of secular trends of thelarche.OBJECTIVES To systematically evaluate published data on pubertal timing based on age at thelarche and evaluate the change in pubertal onset in healthy girls around the world.DATA SOURCES A systematic literature search was performed in PubMed and Embase of all original peer-reviewed articles published in English before June 20, 2019.STUDY SELECTION Included studies used clinical assessment of breast development in healthy girls and used adequate statistical methods, including the reporting of SEs or CIs. The quality of the articles was evaluated by assessing study design, potential sources of bias, main characteristics of the study population, and methods of statistical analysis. DATA EXTRACTION AND SYNTHESISIn accordance with PRISMA guidelines, all articles were assessed for eligibility independently by 2 authors. Weighted regression analysis was performed using a random-effects model. MAIN OUTCOMES AND MEASURESStudies examining age at thelarche (development of Tanner breast stage 2) in healthy girls. RESULTSThe literature search resulted in a total of 3602 studies, of which 30 studies fulfilled the eligibility criteria. There was a secular trend in ages at thelarche according to race/ethnicity and geography. Overall, the age at thelarche decreased 0.24 years (95% CI, −0.44 to −0.04) (almost 3 months) per decade from 1977 to 2013 (P = .02). CONCLUSIONS AND RELEVANCEThe age at thelarche has decreased a mean of almost 3 months per decade from 1977 to 2013. A younger age at pubertal onset may change current diagnostic decision-making. The medical community needs current and relevant data to redefine "precocious puberty," because the traditional definition may be outdated, at least in some regions of the world.

Trends in the Incidence of Central Precocious Puberty and Normal Variant Puberty Among Children in Denmark, 1998 to 2017

“…This was summarized in our 2020 systematic review and meta-analysis 28 of 30 studies including more than 145 000 girls from 7 regions of the world (eg, the United States, Europe, Asia). 28 Although we find the upward trends in incidence of CPP concerning, there has also been considerable debate regarding whether present guidelines of CPP are appropriate in contemporary populations. There may be basis for revision of reference ranges for pubertal onset based on new thorough clinical investigations of CPP diagnosis and interrelation with bone age advancement and hormonal changes in the general population.…”

“…However, more recent European 24,25 and Korean 26,27 studies based on number of prescriptions, medication reimbursements, or data from health insurance agencies have suggested a possible upward trend in the incidence of CPP. Furthermore, a 2020 meta-analysis 28 b Data in the present study were analyzed in main analyses with the 1-year lag for diagnosis (ie, at-risk girls aged 0-9 years; at-risk boys aged 0-10 years) and without the 1-year lag for diagnosis (ie, at-risk girls aged 0-8 years; at-risk boys aged 0-9 years).…”

Association of Early-Life Adversity With Measures of Accelerated Biological Aging Among Children in China

“…Increasing evidence suggests a secular trend for earlier pubertal timing in both boys 22 and girls, 23 which has frequently been associated with various adverse health outcomes over the life span. 24 , 25 , 26 Thus, for our reproductive strategy metric of biological aging, we focused on median age at thelarche and testicular development across 4 repeated annual assessments at baseline (wave 1, in 2016) to wave 4 (in 2019).…”

Minipuberty of human infancy – A window of opportunity to evaluate hypogonadism and differences of sex development?

“…1,2) Thus, we have recently demonstrated in systematic review and meta-analysis a worldwide decline in age at thelarche corresponding to 3 months per decade from 1977 to 2013. 3) The mechanisms behind this secular trend are quite complex and multifactorial. There is a wide interindividual variation in the timing of puberty, which can be partially explained by genetic and environmental changes such as nutrition, but most parts remain unexplained.…”