This is the first description of the characteristics and size of the clitoris in Ghana and the largest cohort of newborn clitoral sizes in published literature. Traditionally, normal clitoral length is accepted as < 1.0 cm, although rare variations exist [16]. In our study, only 3/612 females (0.49%) had a clitoral length ≥ 1 cm. These patients were followed up for a year and their clitoral size did not increase with time, nor did they develop any clinical features suggestive of CAH. Studies in newborns from different parts of the world have reported MCL ranging from 3.1–7.7 mm [10, 13, 17,18,19,20,21]. Most published studies done in newborns did not elaborate on how the clitoral measurements were done. Amongst studies with similar inclusion criteria, our MCL of 4.13 ± 1.60 mm was comparable to the 4.0 ± 1.24 mm reported by Oberfield et al. [17] in United States and the 4.93 ± 1.61 mm reported by Kutlu et al. [10] in Turkey. Our MCL was also similar to that of other studies that involved preterms, including the 3.66 ± 0.13 mm reported by Riley and Rosenbloom [13] in black term and preterm newborns in United States. Mondal et al. [20] also reported a comparable albeit slightly lower MCL of 3.1 ± 1.54 mm in India and Jarrett et al. [19] reported a relatively higher MCL of 7.7 ± 1.37 mm in 244 term and preterm newborns in Nigeria.
A clitoral width > 6 mm has been said to suggest virilization [22], probably based on earlier studies by Riley and Rosenbloom (1980) [13] and Oberfield et al. (1989) [17]; who both reported an upper limit of 6 mm for clitoral width range in newborns. However, the range for clitoral width is not well established as fewer studies have reported clitoral width. In this study, as many as 31 / 612 newborns (5.1%) had a clitoral width greater than 6 mm. These patients were followed up and they remained healthy. Jarrett et al. [19] also reported a clitoral width range of 1–7 mm, and so regional differences in clitoral size may exist. More African data will be needed to clarify this. Our MCW of 4.21 ± 1.1 mm was similar to reports from Jarrett et al. [19] and Yokoya et al. [21] of 4.4 ± 0.89 mm and 4.4 ± 1.2 mm respectively. Oberfield et al. [17] reported a relatively lower mean clitoral width (MCW) of 3.32 ± 0.78 mm in North American term newborns.
Factors that may be responsible for the reported variation in clitoral sizes include differences in study population. Some studies included preterms [13, 19, 20] whereas this study recruited only term newborns. Clitoral size has also been reported to correlate with anthropometric parameters of the study population [10]. Furthermore, differences in tools and techniques of measurement as well as inter observer variability may play a role. This study utilized calipers in the measurement of clitoral length and width while other studies utilized tumorimeters or rulers [19, 23]. MCL have also been reported to vary with ethnicity/race, which may also partly account for the differences in reported values [12, 13].
Only MCW but not MCL in our study was negligibly associated, though inversely, with gestational age. The lack of significant association was not unexpected as all the newborns were full term. The analysis for correlation between maternal herbal intake and clitoral size was done to evaluate for possible hormonal effects of the ingested herbal medicines, since their constituents were largely unknown. There was no significant difference in genital measurements done in the first 24 h and those done afterwards. Oberfield et al. [17] also noted no difference in clitoral sizes when they compared measurements done before and after 24 h in order to evaluate for possible variation from swelling of the genital area due to birth trauma.
Birth weight was inversely associated with both MCL and MCW, implying newborns with a lower birth weight had larger clitoral sizes and vice versa. Similarly, Kutlu and Akbiyik [10] also found a negative correlation between MCL with birth weight. However, unlike this study they also reported a negative correlation between MCL and birth length. Oberfield et al. [17] found no correlation between clitoral size and birth weight or length.
Kutlu and Akbiyik [10] reported that the clitoral length was < 5 mm when it appeared to be covered by the labia majora and concluded that no extra clitoral measurement was clinically indicated in such cases. In our study, the highest recorded MCL and MCW in newborns with completely covered clitoris was 8.3 mm and 6.22 mm respectively. Overall, newborns whose clitoris was completely covered by the labia majora had the lowest mean clitoral size (p < 0.001) and indeed further clitoral measurements may not be indicated in such newborns; as suggested by Kutlu and Akbiyik [10].
One limitation of our study is that measurements were done by two examiners and could have introduced an error due to inter-observer variability. However, an extensive training was done and a subset of study subjects was examined by both 2 examiners to evaluate and control for variability, which remained insignificant throughout the study.