A cross-sectional growth reference and chart of stretched penile length for Japanese boys aged 0-7 years.

Background/Aim: Reference values for penile length have not been established for Japanese boys. We aimed to develop percentiles and means (and standard deviations) of stretched penile length (SPL) in Japanese boys. Methods: A cross-sectional study was performed in 1,628 Japanese boys aged Results: SPL increases continuously during the prepubertal period, and most rapidly in the first 4 months of life. No significant fixed or proportional bias was found for interobserver variation (p = 0.5; r = 0.33, p = 0.06). There was no significant correlation between SPL z-score and stature z-score (r = 0.14, p = 0.09, p Conclusion: These data serve as an updated growth reference for SPL in Japanese boys aged 0-7 years.