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Paediatric penile length: a systematic review and meta-analysis
Fausto Negri1,2,3, Federico Belladelli2,3, Chiyuan A Zhang1
1Department of Urology, School of Medicine, Stanford University, Stanford, CA, USA.
BJU International
|June 14, 2026
Summary
Penile length in prepubertal boys varies significantly by region and age. A concerning trend suggests a decline in stretched penile length over the past two decades, impacting developmental disorder identification.
Area of Science:
- Pediatric endocrinology
- Human growth and development
- Public health
Background:
- Establishing normative data for genital organ size is essential for identifying potential developmental disorders in children.
- Penile length is a key indicator of normal sexual development.
Purpose of the Study:
- To analyze geographical variations in stretched penile length among prepubertal boys.
- To evaluate temporal trends in penile length over the last 20 years.
- To update reference values for genital organ size in pediatric populations.
Main Methods:
- Systematic review and meta-analysis of studies published in PubMed, Cochrane, and Scopus databases.
- Inclusion of 55 studies with quantitative penile length data from 31,915 boys (2000-2024).
- Exclusion of studies involving congenital malformations; risk of bias assessment performed.
Main Results:
- Pooled mean stretched penile length estimates varied by age group, ranging from 3.07 cm (1-week-old) to 5.43 cm (5-10-year-old).
- A significant decrease in stretched penile length was observed from the 2000s to the 2020s, with declines ranging from 16.2% to 26.2% across age groups.
- Subgroup analysis revealed significant geographical variations in penile length for boys over 2 years old (P < 0.001).
Conclusions:
- Prepubertal penile length exhibits considerable geographical variability and age-related differences.
- A potential decline in stretched penile length over the past two decades warrants further investigation.
- Updated reference values are crucial for accurate assessment and early detection of disorders.
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