ESPE Abstracts

Background: Associations between foetal androgen deficiency and variations in anogenital distance (AGD) suggest that AGD is a reliable indicator of foetal androgen exposure. Similarly, variation in postnatal penis growth associated with variations in testosterone show penis growth to be a potential biomarker of early postnatal androgen exposure. Though variation in early androgen exposure is also hypothesized to underlie neurobehavioral masculinisation, until now, no reports have linked either biomarker to human sex-related behaviour.

Objective and hypotheses: To investigate the potential utility of employing biomarkers of foetal and neonatal testosterone exposure as predictors of neurobehavioral masculinisation. We hypothesized that birth AGD and early neonatal penis growth would each contribute unique variance in explaining male-typical behaviour in boys.

Method: As part of a large birth cohort study, measurements of AGD, penis length, and body length were taken in typically-developing boys at birth and at 3, 12, 18, and 24 months postnatally. Behaviour was measured in 81 boys (mean age 3.88 years, S.D. 0.55) using the Preschool Activities Inventory (PSAI), a reliable and validated measure of sex-typed behaviour in children. Multiple regression was used for analysis.

Results: Measurements suggested typical childhood development. Also, as predicted, the overall model was significant (R²=0.23, P≤0.01) and birth AGD (β=0.240, P<0.05) and penis growth from birth to 3 months (β=0.481, P≤0.001) accounted for significant unique variance in PSAI scores, when controlling for penis length at birth, subsequent penis growth to 24 months, and body growth to 12 months.

Conclusion: AGD and penis growth may provide a readily available methodology for assessing independent exposures to foetal and neonatal testosterone in boys. Findings also provide the first evidence of the importance of the postnatal testicular surge, independent of androgen exposure prenatally, in human neurobehavioral masculinisation.