To update the normal stretched penile length values for children younger than 5 years of age. We also evaluated the association between penile length and anthropometric measures such as body weight, height, and body mass index.

The study was performed as a cross-section study. The stretched penile lengths of 1040 white uncircumcised male infants and children 0 to 5 years of age were measured, and the mean length for each age group and the rate of increase in penile length were calculated. The correlation between penile length and weight, height, and body mass index of the children was determined by Pearson analysis.

The stretched penile length was 3.65 ± 0.27 cm in full-term newborns (n = 165) and 3.95 ± 0.35 cm in children 1 to 3 months old (n = 112), 4.26 ± 0.40 cm in those 3.1 to 6 months old (n = 130), 4.65 ± 0.47 cm in those 6.1 to 12 months old (n = 148), 4.82 ± 0.44 cm in those 12.1 to 24 months old (n = 135), 5.15 ± 0.46 cm in those 24.1 to 36 months old (n = 120), 5.58 ± 0.47 cm in those 36.1 to 48 months old (n = 117), and 6.02 ± 0.50 cm in those 48.1 to 60 months old (n = 113). The fastest rate of increase in penile length was seen in the first 6 months of age, with a value of 1 mm/mo. A significant correlation was found between penile length and the weight, height, and body mass index of the boys (r = 0.881, r = 0.864, and r = 0.173, respectively; P = 0.001).

The age-related values of penile length must be known to be able to determine abnormal penile sizes and to monitor treatment of underlying diseases. Our study has provided updated reference values for penile lengths for Turkish and other white boys aged 0 to 5 years.