Morphokinetic parameter S2 predicts early embryo developmental potential and associated metabolic pathways.

Area of Science:

• Reproductive Medicine
• Embryology
• Metabolomics

Background:

• Assessing early embryo developmental potential is crucial for successful IVF outcomes.
• Morphokinetic parameters derived from time-lapse imaging offer insights into embryo development.
• The S2 parameter, representing the 3-cell to 4-cell cleavage duration, warrants further investigation for its predictive value.

Purpose of the Study:

• To determine the predictive value of the S2 morphokinetic parameter for early embryo developmental potential.
• To establish an optimal cutoff value for the S2 parameter.
• To explore metabolic pathways associated with S2 values and embryo development.

Main Methods:

• Prospective analysis of 662 embryos from 65 patients using time-lapse incubators.
• Receiver operating characteristic (ROC) analysis to determine the optimal S2 cutoff for predicting blastocyst formation and quality.
• Metabolomic profiling of spent culture media (SCM) using liquid chromatography-tandem mass spectrometry (LC-MS) stratified by S2 cutoff.

Main Results:

• The S2 parameter demonstrated moderate predictive capacity for blastocyst formation (AUC=0.622) and quality (AUC=0.645).
• An optimal S2 cutoff of 0.7 hours was identified, with significant differences observed between blastocyst formation/quality groups.
• Metabolomic analysis revealed 98 differentially expressed metabolites linked to protein digestion, aminoacyl-tRNA biosynthesis, and fatty acid metabolism.

Conclusions:

• The S2 parameter (cutoff 0.7 h) exhibits moderate predictive value for embryo developmental potential.
• Specific metabolic pathways are associated with S2 regulation, highlighting a link between morphokinetics and metabolism.
• The S2 parameter holds potential for integration into multifactorial embryo evaluation models.