Development and validation of a predictive model for early blastocyst formation on day 4 post-fertilization

Area of Science:

• Reproductive Medicine
• Embryology
• Clinical Prediction Modeling

Background:

• Early blastocyst formation on Day 4 is a critical indicator of embryo viability.
• Predicting this developmental milestone using accessible parameters can optimize embryo transfer strategies.

Purpose of the Study:

• To develop and validate a predictive model for early blastocyst formation on Day 4 post-fertilization.
• To identify clinically accessible parameters that predict Day 4 early blastocyst formation.

Main Methods:

• Retrospective cohort study of 2,557 patients undergoing fresh Day 4 embryo transfer.
• Development and validation of a nomogram model using multivariable logistic regression.
• Model performance assessed using AUC, calibration curves, and decision curve analysis.

Main Results:

• The number of Day 3 embryos with >10 blastomeres and iDAScore >4.8 were independent predictors of Day 4 early blastocyst formation.
• The nomogram demonstrated robust discrimination (validation AUC=0.773) and clinical utility.
• Early blastocyst formation was associated with superior embryo quality and improved pregnancy outcomes.

Conclusions:

• A validated nomogram accurately predicts Day 4 early blastocyst formation using Day 3 embryo parameters.
• Early blastocyst formation on Day 4 may indicate suitability for selective Day 4 embryo transfer.
• This predictive model can enhance embryo selection and improve IVF success rates.