Kisspeptin as a Precision Biomarker in Personalized Pharmacy: Implications for Individualized Monitoring of Early Pregnancy Viability

Background: Precision medicine aims to improve early, individualized risk stratification using biologically relevant biomarkers. In early pregnancy, markers reflecting placental function remain limited. Kisspeptin, a placentally derived peptide that rises during normal gestation, has emerged as a potential indicator of pregnancy viability. Objectives: We aimed to evaluate evidence on maternal serum kisspeptin levels and placental KISS1/KISS1R expression in early pregnancy loss, and to assess its potential relevance as a precision biomarker within personalized pharmacy and individualized monitoring frameworks. Methods: A systematic search of PubMed, Scopus, Web of Science, and Google Scholar (up to 2025) was conducted according to the PRISMA 2020 guidelines. Studies assessing circulating kisspeptin and/or placental expression in early pregnancy loss versus viable pregnancies were included. A formal meta-analysis was not performed due to substantial heterogeneity in study design, biological material, assay methods, gestational age, and outcome reporting formats. Under these conditions, quantitative pooling was considered methodologically inappropriate; therefore, qualitative synthesis was performed. Results: Six studies met the inclusion criteria. Most reported significantly lower maternal serum kisspeptin levels in early pregnancy loss, with good discriminatory accuracy. Immunohistochemical analyses showed reduced placental and choriodecidual KISS1/KISS1R expression in miscarriage and recurrent pregnancy loss, indicating disrupted local signaling. Concordant systemic and tissue findings suggest that circulating kisspeptin reflects placental dysfunction. Conclusions: Kisspeptin appears to be a promising precision biomarker for monitoring early pregnancy viability and supporting individualized pharmaceutical care. Standardized assays and large prospective studies are needed before routine clinical implementation.