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Digit ratio (2D:4D) and maternal testosterone-to-estradiol ratio measured in early pregnancy

Lookup NU author(s): Dr Gareth RichardsORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


The ratio of index to ring finger (2D:4D) has been hypothesised to indicate prenatal androgen exposure, yet evidence for its validity is lacking. We report the first pre-registered study to investigate mothers’ early pregnancy sex hormone concentrations in relation to their children’s digit ratios measured at 18-22-month follow-up. Although the testosterone (T) to estradiol (E) ratio correlated negatively with right hand digit ratio (R2D:4D) and directional asymmetry (right-minus-left) in digit ratio (D[R-L]), neither effect remained statistically significant once demographic and obstetric covariates were controlled for. Nevertheless, the multivariate level of analysis did reveal that T correlated positively with left hand digit ratio (L2D:4D) and negatively with D[R-L]. However, the first of these effects is in the opposite direction to that predicted by theory. Taken together, the results of our study suggest research with larger samples is required to determine whether digit ratios are valid proxies for maternal sex hormone exposure.

Publication metadata

Author(s): Richards G, Aydin E, Tsompanidis A, Padaigaitė E, Austin T, Allison C, Holt R, Baron-Cohen S

Publication type: Article

Publication status: Published

Journal: Scientific Reports

Year: 2022

Volume: 12

Online publication date: 09/08/2022

Acceptance date: 22/07/2022

Date deposited: 22/07/2022

ISSN (electronic): 2045-2322

Publisher: Nature Publishing Group


DOI: 10.1038/s41598-022-17247-3


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Funder referenceFunder name
777394IMI Joint Undertaking
Autism Research Trust
Wellcome Trust
Templeton World Charitable Fund