Worldwide Secular Trends in Age at Pubertal Onset Assessed by Breast Development Among Girls: A Systematic Review and Meta-analysis.
Level 3 - non-randomized controlled study
Systematic review of observational/cross-sectional studies assessing age at pubertal onset.
PubMed 32040143 · doi:10.1001/jamapediatrics.2019.5881
What was done
Authors conducted a systematic review and meta-analysis across PubMed and Embase for English-language peer-reviewed studies published before June 20, 2019. Eligible studies evaluated healthy girls using clinical assessment of breast development (Tanner stage 2 / thelarche) and reported standard errors or confidence intervals. Two independent reviewers assessed study quality and bias. A weighted random-effects meta-regression model was used to evaluate temporal trends in the age of pubertal onset globally.
What was found
From 3,602 screened records, 30 studies met inclusion criteria. Age at thelarche showed secular variations across race/ethnicity and geographic regions. Across all included studies, the overall mean age at thelarche decreased by 0.24 years (95% CI, -0.44 to -0.04) per decade between 1977 and 2013 (P = .02), translating to an advance of almost 3 months per decade.
Why it matters
This confirms a global secular decline in the age of female pubertal onset using clinical breast staging rather than recalled age at menarche. These findings indicate that traditional clinical definitions for precocious puberty may require revision to prevent inappropriate diagnostic workups.
Limits
The analysis was restricted to English-language publications and included only 30 studies across the globe, limiting geographic granularity. The underlying studies are observational and subject to population heterogeneity, and the abstract provides no data on potential confounding drivers such as body mass index changes, socioeconomic status, or environmental exposures.
Cited by
- supports The average age of puberty onset has been continuously falling with every successive historical cohort.