As modern society has became more open, interest in healthy internal and external growth has increased, including that pertaining to penile length in children. A micropenis is defined as one where penile length is more than 2 SD (standard deviation) below the mean, and it can be traced back to chromosome and endocrine disorders. The authors executed this study to suggest guidelines for the study of the micropenis and standard information for penile length in Korean newborns.

The subjects of this study were 168 male infants between 37 and 42 weeks of gestational age, none of whom had any complications during pregnancy or birth; each had been born in Daegu Fatima Hospital between February and June 2007. Penile length was measured using conventional stretched penile length measurement (CPLM) and syringe methods.

Penile length was 3.02±0.25 cm (F=36.467, R²=0.180, P <0.001) when measured with CPLM, and 3.29±0.26 cm (F=9.149, R²=0.052, P <0.001) with the syringe method. There was no statistically significant difference in the penile length of newborn infants as a result of taking measurements with the two methods, and both methods showed significance at 0.631 in terms of Pearson's correlation coefficient, at the level of P =0.01.

In this study, penile length tended to be longer when gestational age was longer, and a micropenis can be assumed to be one less than 2.5 cm using CPLM and less than 2.8 cm using the syringe method. In the case of a concealed penis, the syringe method is helpful. When a micropenis is assumed, close observation by outpatient department personnel, and additional endocrine and chromosome studies should be undertaken after sufficiently consulting the parents.