Estimation of Reference Values for External Genitalia Parameters in North Indian Preterm and Term Male Newborns

To generate gestation-wise normative data of external genitalia measurements in North Indian term and preterm male newborns.

This was a hospital-based cross-sectional observational study. Male neonates born between 28-42 wk of gestation (at 24-72 h of life) were consecutively recruited in the study. Newborns with major congenital malformations, chromosomal anomalies, multifetal gestation and birth injuries were excluded. Data on various genital measurements were collected [Stretched penile length (SPL), penile width (PW), upper anogenital distance (AGDu), lower anogenital distance (AGDl) and anogenital ratio (AGR)].

Out of 532 newborns, 208 (39.1%) were preterm. Mean (± SD) SPL and PW were 27.9 ± 3.6 mm and 10.6 ± 1.3 mm respectively. The mean values for AGDl, AGDu and AGR were 20.13 ± 4.04 mm, 39.2 ± 5.59 mm, and 0.51 ± 0.07, respectively. SPL less than 21 mm in a term male newborn and 17.5 mm in preterm should be considered micropenis (<2.5 SD) in our population. Gestation-wise percentile charts for SPL, PW, AGDl, AGDu and AGR were generated.

The reference values and percentile charts generated can serve as local normative data for accurate interpretation of genital measurements in North Indian newborns, assessment of ambiguous genitalia and avoiding diagnostic errors.