Normative penile anthropometry in term newborns in Kumasi, Ghana: a cross-sectional prospective study

BACKGROUND Genital measurements are a useful adjunct in the early detection of various endocrine conditions including hypopituitarism and disorders of sexual differentiation. Standards for genital sizes have been published but racial/ethnic differences exist. This study was done to establish norms for genital sizes in term Ghanaian male newborns. METHODS This was a cross-sectional study of all apparently well full-term newborns of postnatal age < 48 h and birth weight between 2.5 and 4.0 kg delivered at Komfo Anokye Teaching Hospital within the study period. Anthropometric and genital parameters were documented for study subjects as well as parental socio-demographic indices. RESULTS A total of 644 male newborns were recruited between May and September 2014. The mean penile length (MPL) was 3.3 ± 0.5 cm and the mean penile width (MPW) was 1.05 ± 0.1 cm. An inverse relationship was found between maternal age and MPL (correlation coefficient -0.062, 95% CI -0.121 to -0.002; p = 0.04). MPL was also significantly different (p = 0.04) by mode of delivery, with babies delivered by caesarean section having the lowest MPL. MPL correlated positively with both gestational age (p = 0.04) and birth length (p < 0.001), while MPW correlated proportionally with birth weight and length (p < 0.001 for both). CONCLUSIONS Using the conventional definition of micropenis as stretched penile length (SPL) < 2.5 standard deviation (SD) below the mean and macropenis as an SPL > 2.5 SD, a Ghanaian term newborn may warrant investigation if he has an MPL < 2.1 cm or > 4.4 cm.