Assessing Gestation and Fetal Sex in Wild Assamese Macaques Using Urinary Estrogen Analysis.

Area of Science:

• Reproductive biology
• Primate endocrinology
• Conservation science

Background:

• Estrogens and progestogens are vital for mammalian pregnancy and maternal preparation.
• Hormone measurement aids in pregnancy diagnosis, failure estimation, and prenatal sex determination.
• Noninvasive biomarkers are crucial for monitoring wildlife reproduction.

Purpose of the Study:

• To evaluate urinary estrogen and progestogen metabolites as biomarkers for gestation detection in Assamese macaques.
• To assess the utility of these metabolites for fetal sex determination.
• To understand steroid hormone metabolism in this primate species.

Main Methods:

• Collected 586 urinary samples from 19 wild Assamese macaques across various reproductive stages.
• Tested four enzyme-immunoassays for measuring urinary sex steroid metabolites.
• Validated hormone assays using serial dilution and biological samples from one female across gestation.

Main Results:

• Urinary estrone conjugates (E1C) increased during gestation and declined sharply at parturition.
• Progestogen metabolites did not reflect gestational status.
• Higher E1C levels were observed in late gestation for females carrying male fetuses compared to female fetuses, with overlapping values.

Conclusions:

• Urinary E1C is a reliable noninvasive marker for gestation monitoring in Assamese macaques.
• E1C shows potential for fetal sex determination, though precision is limited.
• Species-specific differences in steroid hormone metabolism necessitate careful marker selection for reproductive monitoring.