Dehydroepiandrosterone and dehydroepiandrosterone-sulfate: Biomarkers of pregnancy and of fetal health

Abstract

Dehydroepiandrosterone (DHEA) and its sulfate (DHEAS) are important estrogen precursors, secreted mainly by the adrenal cortex. At late gestation, both DHEA and DHEAS (DHEA(S)) are produced at high concentrations in some species due to the developing fetal adrenal gland. Failure in DHEAS increase during late gestation can indicate fetal death, which prompts its use as a biomarker of pregnancy and fetal health in wildlife. Here, we review the most common non-invasive biomarkers of reproduction in wildlife, the molecular mechanisms of DHEAS synthesis and action during gestation, in addition to the advantages and limitations of incorporating DHEA(S) in these studies. Using previously published data, we tested the specificity and sensitivity of fecal DHEAS as a predictor of successful gestation in four captive primate species (orangutans (Pongo pygmaeus), siamangs (Symphalangus syndactylus), Japanese macaques (Macaca fuscata), and howler monkeys (Alouatta caraya)). Using data from non-pregnant/non-lactating females, we set a threshold on fecal DHEAS levels for detecting successful pregnancy per species, controlling for age and housing condition (social vs single). We found that DHEAS had 100% specificity for all species (non-pregnant samples were below the threshold for pregnancy), and 100% sensitivity for Japanese macaques housed individually, and for orangutan and siamangs (all samples from successful pregnancies were above the threshold, and all samples from stillbirth were below the threshold). However, the sensitivity was 80% in howler monkeys and 50% in Japanese macaques housed socially. Our preliminary results indicate that, while DHEAS is a promising biomarker of fetal health, it is limited to late gestation and to some species. We suggest increasing the sample size to calculate the pregnancy threshold per species and to test multiple samples from the same individual when using this method.