Inner Cell Mass Grade and Earlier Blastulation Are Associated with Pregnancy Outcomes in Euploid Embryos

Area of Science:

• Reproductive Medicine
• Embryology
• In Vitro Fertilization (IVF)

Background:

• Assessing factors influencing live birth after euploid embryo transfer is crucial for optimizing IVF success.
• Inner cell mass (ICM) and trophectoderm (TE) quality are key indicators of embryo viability.
• Understanding the role of blastulation timing and embryo sex in live birth outcomes is important for clinical decision-making.

Purpose of the Study:

• To evaluate the association between blastulation timing, ICM/TE quality, embryo sex, and embryo sex selection with live birth rates in euploid embryos.
• To identify embryo characteristics that can predict successful pregnancy outcomes following frozen embryo transfer (FET).
• To determine if embryo sex or sex selection influences live birth rates among euploid embryos.

Main Methods:

• Retrospective cohort analysis of 768 euploid frozen embryo transfer cycles from 2020-2021.
• Embryos were graded for ICM and TE quality prior to vitrification.
• Mixed-effect multivariable logistic regression was used to assess associations between live birth and patient/embryo characteristics.

Main Results:

• Live birth occurred in 52.6% of cycles.
• Lower odds of live birth were associated with vitrification on days 6-7 compared to day 5 (aOR 0.81).
• Embryos with lower ICM quality had significantly lower odds of live birth compared to those with quality 1 (aOR 0.75).
• Embryo sex and embryo sex selection were not significantly associated with live birth odds.

Conclusions:

• Prioritizing embryos with earlier blastulation (day 5) and superior ICM quality may enhance the probability of live birth.
• Trophoblast quality, embryo sex, and embryo sex selection did not demonstrate a significant association with live birth odds in this cohort.
• While not statistically significant, embryo sex and sex selection may still influence clinical decision-making in embryo transfer.