Decoding the silent language of embryos: current evidence, clinical applicability and future perspectives of non-invasive embryo assessment in IVF

Abstract

Non-invasive embryo assessment strategies are increasingly being explored in in vitro fertilization (IVF) to complement conventional morphological evaluation and improve embryo selection. This narrative review provides a comprehensive overview of current and emerging approaches, with a focus on time-lapse monitoring (TLM), artificial intelligence (AI), omics-based technologies and non-invasive genomic testing, and critically evaluates their clinical utility and limitations. Recent literature investigating morphokinetic parameters, AI-based embryo evaluation, transcriptomic, metabolomic and secretomic biomarkers, and non-invasive preimplantation genetic testing was reviewed, including relevant clinical studies, systematic reviews and guideline-based recommendations. TLM enables continuous monitoring of embryo development and provides morphokinetic information associated with developmental competence; however, randomized clinical evidence has not demonstrated a consistent improvement in clinically meaningful outcomes when TLM-based embryo selection is used in isolation. AI-based models may improve the objectivity and reproducibility of embryo evaluation, but heterogeneous predictive performance, limited external validation and insufficient evidence of improved live birth outcomes currently support their use primarily as decision-support tools. Omics-based approaches have identified potential non-invasive biomarkers associated with embryo competence and implantation, although methodological variability, lack of standardization and limited prospective validation continue to restrict clinical translation. Among non-invasive genomic approaches, cfDNA-based non-invasive preimplantation genetic testing for aneuploidy (niPGT-A) has shown promising potential, but variable concordance with trophectoderm biopsy and insufficient clinical validation currently preclude its use as a replacement for conventional PGT-A. More comprehensive genomic applications of embryo-derived cfDNA remain exploratory. Overall, embryo assessment is evolving toward integrative, multidimensional strategies combining morphological, developmental, molecular and computational information. Despite substantial technological advances, most emerging non-invasive approaches remain investigational or experimental, and rigorous standardization, multicentre prospective validation and demonstration of improvements in clinically meaningful outcomes are required before routine clinical implementation.