Growth and Maturation in the Male Genitalia From Birth to Adolescence II. Change of Penile Length

Penile lengths of Japanese males from birth to adolescence were studied in cross‐sectional series. The mean length of the penis in 5 days term newborn was 2.9 ± 0.5 cm (M ± SD). There was a gradual increase in penile length from the age 1 to 11 years. After 12 years of age there was a sudden increase in length. The mean length increased from 5.5 ± 1.5 cm at the age of 12 to 8.3 ± 0.8 cm at 14 years. The largest increment was observed between the age of 13 and 14 years. Mean penile length increased from 4.9 ± 0.8 cm at stage I of pubic hair development to 7.2 ± 1.4 cm at stage II and 9.0 ± 1.0 cm at stages IV‐V. The largest increment was observed between stage I and stage II of pubic hair development. This new reference of penile length can be helpful in those cases in which the children is suspective of having genitals of abnormal size.