Prospective Observational Pilot Study of Discarded Blastocysts: a Molecular Approach to Uncovering Hidden Reproductive Potential

In vitro fertilization has advanced infertility treatment, but accurately assessing embryo viability remains challenging because conventional selection methods may miss subtle molecular indicators of developmental potential. Increasing evidence shows that some embryos discarded based on morphology or developmental timing may be chromosomally normal and possess favorable molecular traits, prompting interest in multiomics analysis as a more sensitive assessment tool. Studies have demonstrated that omics patterns can distinguish chromosomally normal from abnormal embryos and correlate with key indicators of developmental competence, such as morphology, arrest status, and implantation success, with high-potential blastocysts showing distinct developmental gene signatures. The blastocyst stage is particularly critical, as inner cell mass (ICM) and trophectoderm (TE) lineages diverge, and emerging data suggest these cell types exhibit different multiomics responses to chromosomal abnormalities. However, many prior studies relied on vitrified embryos, where cryopreservation may alter multiomic profiles.

To address this limitation, this study focuses on fresh, non-vitrified blastocysts, offering a more accurate representation of embryos' intrinsic molecular states and developmental potential. Therefore, the aim of the present pilot study is to define multiomics patterns associated with euploidy, chromosomal abnormalities and embryo quality at the blastocyst stage.

Once the study is approved by the competent Research Ethics Committee, the recruitment and selection of patients will follow. Every potential participant will be asked to sign the study informed consent. To comply with the study design and the proposed hypothesis, an estimated total number of 150 patients will be recruited to obtain around 200 discarded embryos.

This is a prospective, descriptive, observational pilot study which will include all eligible discarded blastocysts donated by IVF patients from a single Norwegian centre. This site will be responsible for patients' recruitment and embryonic samples collection, while sample analysis will take place in a Central Laboratory in Spain. On day 5/6 of development, blastocysts that do not meet the standard clinical criteria to be transferred, will be donated to the study by the participants. Additionally, when possible, cumulus cells and sperm cells will also be collected. After embryo donation, 2 trophectoderm and 1 inner cell mass biopsies will be collected and analysed for multiomics profiling.

Data exported from the medical records and source documents will be duly codified to protect the clinical and personal information of patients in accordance with the current legislation on data protection. This information will be exported to an internal database.