Neonatal stretched penile length: relationship with gestational maturity and anthropometric parameters at birth

It is inappropriate to use universal cut-off points to interpret stretched penile length (SPL) measurements in newborns with variable body dimensions.

To assess neonatal SPL on the basis of gestational maturity and anthropometric parameters at birth.

A cross-sectional observational study of SPL was conducted on stable newborns at a referral teaching hospital in north India between January and June 2012. Gestational maturity, SPL and anthropometric parameters (weight, length, head circumference and foot length) were recorded within 24 hours of birth. Variation of SPL in relation to gestational age and anthropometric parameters were evaluated using multiple linear regression models. The equation using lower confidence limits of 95% confidence intervals for the correlation coefficients provides cut-off points to define a small penis.

Data from 1249 newborns demonstrated that penile growth follows the pattern of increase in body dimensions in newborns. SPL can be predicted best in relation to body and foot length taken together.

SPL should be interpreted in relation to anthropometric parameters in newborns, particularly body and foot length.