A predictive model for the usable blastocyst based on the morphokinetic and morphologic parameters of day 3 embryos

Abstract

Background: Transferring a single blastocyst with high implantation potential reduces the likelihood of a multiple pregnancy. However, blastocyst transfer requires long-term culture, increases laboratory work, and increases the risk of having no embryo for transfer. This study aimed to establish a predictive model for developing usable blastocysts based on the morphokinetic and morphologic features of day 3 embryos. Methods: This retrospective cohort study was performed at IVFAS, An Sinh Hospital, Viet Nam. Cycles in which patients ≤ 38 years old were undergoing intracytoplasmic sperm injection treatment and had embryos cultured in a time-lapse monitoring system were included. Patients who had been treated by in vitro maturation, who used surgically retrieved sperm, or who had polycystic ovary syndrome were excluded from the study. The independent t-test was performed to analyze continuous data, while the chi-square test was used to investigate categorical variables. Statistical significance was defined by a p-value < 0.05. Multivariate logistic regression analysis evaluated the relationship between statistically significant variables and blastocyst formation. Results: From March 2016 to August 2018, 1,629 embryos extracted from 169 women were collected. The average patient age and anti-Müllerian hormone levels were 32.02 ± 3.77 years and 5.62 ± 3.89 ng/ml, respectively. Using Bayesian model averaging and multivariate logistic regression, the number of blastomeres, fragmentation rate, and time of division to five cells (t5) were identified as the most predictive factors. The final model had an under the receiver operating characteristic curve of 0.77 (95% confidence interval = 0.74 – 0.79), and the predicted and observed probabilities of the usable blastocyst did not significantly differ (Hosmer-Lemeshow test, p > 0.05). Conclusion: The number of blastomeres, fragmentation rate, and t5 value can be used to predict usable blastocyst formation from the embryo at the cleavage stage.