Clinical Validation of Self-Measurement for Anogenital Distance in Women

Anogenital distance (AGD), the length from the anus to specific genital landmarks, is a well validated, testosterone sensitive, sexually dimorphic biomarker used in many kinds of medical and evolutionary research in diverse species of mammals, including humans. Current research into the effects of testosterone on womens reproductive health and disease is motivating increased interest in measuring female AGD. Studies quantifying female AGD typically employ a clinician, such as a gynecologist or nurse, to conduct the measurements. This methodology maximizes accuracy but imposes notable limitations on data collection. All participants submitted self-measurements online and completed a small set of questionnaires, including tests assessing spatial cognition. The accuracy of AGD self-measurements, based on agreement between self- and clinic-measurements, was moderate. Measurement accuracy was predicted by performance on the mental rotation test, such that women who performed better on this test demonstrated greater accuracy in measuring the anus to posterior fourchette distance. We describe ideas for improving the accuracy of the self-measurement technique. Self-measurement of AGD would increase the number and diversity of women represented in studies of reproductive health, reduce research expenses, and expedite research into the effects of prenatal testosterone and endocrine disruption on female health and disease.