Preimplantation embryo ploidy status correlates with morphokinetic cell cycle timing

Abstract

Objective To determine if morphokinetic parameters differ between euploid and aneuploidy emryo development using time-laps imaging (TLI) and preimplantation genetic screening (PGS). Design Retrospective chart review Materials and Methods A total of 613 embryos from 128 patient couples were evaluated for ploidy status and morphokinetic time points using TLI January,2016- March,2017 were analyzed for TLI, ploidy status and infertility diagnosis. The subject population included couples going through IVF using TLI culture and PGS testing by NGS or aCGH. Important morphokinetic cell divisions were annotated: 2-9+ cell stages annotated as t2, t3, t4, t5, t6, t7, t8 and t9+ and morula formation), starting blastulation(tSB), expanding blastocyst(tEB), and hatching blastocyst(tHB) determined. The Chi square test was used to detect associations between ploidy status,age,infertility diagnosis and PGS results. Two sample student t test was used to compare the difference in average morphokinetic outcomes, t2-t8, between euploid and aneuploid embryos. Cell cycle time between the 2 and 3 cell stage (CC2) and between the 3 and 4 cell stage (S2) were calculated. As these differences lack the normality assumption, we analyzed the difference between CC2 and S2 by using Wilcoxon-Mann Whitney U test to compare between aneuploidy and euploid PGS results. Diagnosis comparisons displayed as descriptive statistics. Results There were no significant differences in most morphokinetic time points between euploid and aneupliod embryos. There was a statistically significant difference between euploid and aneuploid development in the CC2 (-1.088±7.093; p-value= 0.0404) as well as a marginal difference between euploid and aneuploid embryos is S2 (0.963±0.0512; p-value= 0.0512) . It is noticed that ploidy status significantly different between female ≤ 34 yrs. and > 34 yrs. of age (p-value=0.043). The odds of euploid among female ≤ yrs. is 1.465 times compared to that of females > 34 yrs. old. Therefore, younger females are 47% more likely to have euploid embryos compared to older women. Conclusions The observation and comparison of kinetic behavior through TLI and morphokinetic calculations of CC2 and S2 can aid in prediction of embryo ploidy status in combination with PGS test results.