The relationship between offspring's 2D:4D ratio and postpartum maternal circulating testosterone, estradiol, and their indices in a Ghanaian population

Abstract

Objectives The 2D:4D ratio is influenced by prenatal testosterone (PT) and estrogen (PE) exposure in utero. This study sought to determine whether evidence of Manning's hypothesis can still be observed even in the postpartum period. We hypothesize that the offspring 2D:4D ratios will be inversely correlated with maternal postpartum circulating testosterone but positively correlated with estradiol. Methods This study was conducted between December 2020 and April 2021 and was cross‐sectional in nature. There were 272 mother‐offspring pairs; the mothers were aged between 18 and 36 years while the median (IQR) age of their offspring was 111 (44–210) days. Offspring right (2D:4DR) and left (2D:4DL) digit ratios were measured using computer‐assisted analysis. Sampling was done at 111 (44–210) days postpartum and blood was analyzed for total testosterone (TT), estradiol (E2) and sex hormone‐binding globulins using the enzyme‐linked immunosorbent assay technique. Results The 2D:4DR of sons was significantly lower compared to daughters (p = .031). Mothers with sons had significantly increased levels of serum TT (p = .001) while mothers with daughters had significantly increased levels of E2 (p = .000). As hypothesized, the maternal serum free testosterone (FT%) was inversely correlated with their daughters' (r = −0.320, p = .003), and also with their sons' (r = −0.213, p = .047), 2D:4DL. Unexpectedly, daughters' 2D:4DL was inversely correlated with maternal circulating free E2 (r = −0.255, p = .015). Conclusions In humans, evidence of the relationship between maternal testosterone levels and their offspring's 2D:4D ratio may persist even into the postpartum period.

Sex‐moderated relationship between the 2D:4D ratio and circulating hormones in an adult Ghanaian population

“…Research has shown that hormonal variables and the 2D:4D ratio show ethnic, population, and sub‐population variabilities (Manning et al, 2007 ; Manning, Fink, et al, 2022 ). Although the relationship between infant 2D:4D and maternal postpartum circulating hormones has been studied previously (Banyeh et al, 2021 ), there has not been any study in Ghana that has explored the relationship between the 2D:4D ratio and adult circulating hormones. This study aimed to determine the sex‐moderated relationship between the 2D:4D ratio and adult circulating testosterone, estradiol, testosterone‐to‐estradiol ratio, and the free androgen index.…”