Clinical, metabolomic, and proteomic profiles associated with reproductive outcomes in unexplained recurrent pregnancy loss

To identify preconception clinical and multi-omics factors associated with conception and early pregnancy loss in women with unexplained recurrent pregnancy loss (URPL).

In this prospective cohort study, 149 women with URPL selected from 420 outpatients based on guideline-recommended criteria were enrolled between November 2024 and May 2025 and followed-up for 12 months. Preconception fasting plasma was analyzed for clinical biomarkers, untargeted metabolomics, and data-independent acquisition proteomics. Outcomes included conception, ongoing pregnancy beyond 12 weeks and early pregnancy loss before 12 weeks. Multivariable logistic regression was used to evaluate the associations of clinical and multi-omics factors with reproductive outcomes, adjusting for maternal age, body mass index, number of prior losses, and use of assisted reproductive technology.

Of 149 women, 99 conceived (66.4%) during the follow-up. By 12 weeks of gestation, 67 (67.7%) had ongoing pregnancies and 32 (32.3%) experienced early pregnancy loss. Higher testosterone was associated with lower probability of conception (adjusted odds ratio [aOR] 0.50, 95% confidence interval [CI] 0.28-0.89, p = 0.019). Women who conceived showed higher levels of progesterone-related metabolites, including 17-hydroxyprogesterone (fold change, FC = 3.89), pregnanediol 3-O-glucuronide (FC = 2.37), and pregnanetriol 3α-O-β-D-glucuronide (FC = 2.39). Among women who conceived, higher prolactin was associated with higher odds of early pregnancy loss (aOR 1.09, 95% CI 1.01-1.18, p = 0.036), and anti-phosphatidylserine/prothrombin showed a borderline association (aOR 1.07, 95% CI 1.00-1.14, p = 0.052). Early pregnancy loss was characterized by lower bile acid-related metabolites and higher caffeine and methylxanthine metabolites. Proteomic analysis showed enrichment of bile acid biosynthetic process. After adjustment, higher 7α,12α-dihydroxy-3-oxocholest-4-en-27-oic acid was associated with lower odds of early pregnancy loss (aOR 0.64, 95% CI 0.44-0.95, p = 0.025).

Higher testosterone was associated with lower odds of conception. Among women who conceived, early pregnancy loss was associated with higher prolactin, borderline higher anti-PS/PT, lower bile acid-related metabolites, and higher caffeine-related metabolites, with 7α,12α-dihydroxy-3-oxocholest-4-en-27-oic acid identified as an exploratory metabolomic candidate. These findings suggest that potential androgen-related biology, prolactin, non-criteria antiphospholipid antibodies, and bile acid metabolism may be associated with reproductive outcomes in URPL, warranting validation in independent cohorts.