Time-lapse morphokinetic parameters and implantation outcomes of single euploid embryo transfers.

The study explores the factors influencing the implantation success rate of euploid embryos. We primarily aim to understand the relationship between morphokinetics and implantation outcomes, considering potential confounding variables such as maternal age and morphological features of the embryos. Additionally, we intend to elucidate the role of morphological grading in the interplay between morphokinetics and implantation rates in euploid single embryo transfers. The present retrospective study was conducted between January-2016 and January-2023 in a tertiary university hospital's IVF clinic. Forty-four patients who were followed up in time-lapse incubation (Embryoscope, VitroLife) after intracytoplasmic sperm injection (ICSI) procedure were included. All embryos were individually cultured in a time-lapse incubator from ICSI up to the stage of trophectoderm biopsy. Images were recorded with the use of the integrated microscope in every 15 minutes from seven different focal planes. All annotations were made in a prospective fashion by single experienced senior embryologist. A longitudinal dataset containing information on individuals over time was used with a multilevel modeling approach. A linear mixed-effects model was used to analyze the data. The outcome variable (implantation) was modeled as a function of the time intervals, with random effects for the individual. The significance of the fixed effects was tested using a likelihood ratio test. A p-value of less than 0.05 was considered statistically significant. In 44 transferred single euploid embryos, 30 were implanted (68.1%). There was no marked disparity in demographic distributions between the failure or successful implantation groups (for female age, median (IQR) 39.0 (35.5 to 40.0) vs. 39.0 (34.0 to 40.0), p =.751; for male age, median (IQR) 41.5 (38.2 to 43.8) vs. 39.5 (36.0 to 42.8), p=.318; for BMI median (IQR) 23.3 (21.5 to 25.9) vs. 24.7 (23.3 to 28.2), p=.212). Regarding morphological factors, a significant correlation between inner cell mass (ICM) grade and implantation rate was found (p=.001), but it was not observed in trophectoderm grades (p=.103). In the LME (both fixed and random effects were used) model (fixed effects coefficients were the morphokinetic parameters, random effects were the individual embryos, and the outcome was implantation), a significant negative trend was demonstrated between the delay in the last quartile of embryo timeline and implantation. Specifically, a 50% decline in implantation rates was observed in the last quartile with a 9-hour delay (p=.0369, standard error=.3692). However, adding ICM grades to the LME model diminishes the negative trend (p=.99575). The study indicates that morphokinetics may play a role in the success of euploid single embryo transfer procedures, especially within specific temporal windows might impact implantation rates in euploid SET. However, association is diminished when considered with morphological grading of the embryo. [ABSTRACT FROM AUTHOR]