[How can we nowadays select the best embryo to transfer?]

Area of Science:

• Reproductive medicine and embryology.
• Genetics and genomics.
• Biomarker analysis.

Context:

• Multiple pregnancies are a significant risk in assisted reproduction technologies (ART).
• Elective single embryo transfer (e-SET) has improved safety by reducing multiple pregnancies.
• Current embryo selection methods require enhancement for optimal implantation prediction.

Purpose:

• To review and evaluate current and emerging methods for improving embryo selection in ART.
• To assess the efficacy of embryo morphology, time-lapse imaging, and preimplantation genetic screening (PGS).
• To explore novel non-invasive techniques for assessing embryo viability.

Summary:

• Embryo morphology analysis is a primary criterion for selection, while time-lapse imaging offers additional predictive insights.
• Extended embryo culture to blastocyst stage is beneficial, particularly for good-prognosis cases.
• Preimplantation genetic screening (PGS) using comparative genomic hybridization (CGH) on blastocyst biopsies shows promise, unlike older fluorescence in situ hybridization (FISH) methods.
• Non-invasive biomarker analysis in culture media is a potential future method for assessing embryo physiology.

Impact:

• Enhanced embryo selection strategies can increase pregnancy and delivery rates in ART.
• Minimizing multiple pregnancies through e-SET and improved selection reduces maternal and neonatal risks.
• Advancements in embryology and genetic testing contribute to more effective and safer fertility treatments.