P-120 Morphokinetic behavior in embryos leading to biochemical pregnancy

Abstract Study question Does embryos leading to biochemical pregnancy behave morphokinetically different than those leading to positive or negative pregnancy result? Summary answer Embryos that resulted in a biochemical pregnancy did not display evidence of abnormal morphokinetics on time-lapse imaging. What is known already One of the possible outcomes of the pregnancy test is a biochemical pregnancy; where the pregnancy test is positive but does not progress into a clinical pregnancy. Despite its unknown etiology, several associated factors have been suggested such as embryo aneuploidy, abnormal uterine lining, sperm DNA damage and so on. Embryo monitoring with timelapse imaging (TLI) may be a valuable approach to evaluate whether embryonic morphokinetics can predict the occurrence of a biochemical pregnancy. The aim of this study was to investigate whether embryos leading to biochemical pregnancy behave morphokinetically different than those leading to positive or negative pregnancy result. Study design, size, duration This cohort study was performed in a private university–affiliated IVF center between March/2019 and April/22. 753 women undergoing ICSI were split into three groups according to the pregnancy outcome: Biochemical Group (n = 30 cycles and 54 transferred embryos); Positive Group (n = 255 cycles and 444 embryos); and Negative Group (n = 468 cycles and 750 embryos). Generalized mixed models followed by Bonferroni post-hoc test were used to compare morphokinetics among the groups (post hoc achieved power 90%). Participants/materials, setting, methods Injected oocytes were cultured in the EmbryoScope+ incubator, which recorded the following kinetic markers: timing to pronuclei appearance and fading (tPNa and tPNf), two (t2), three (t3), four (t4), five (t5), six (t6), seven (t7), and eight cells (t8), morulae (tM), start of blastulation (tSB) and blastulation (tB). Durations of second and third cell cycles (cc2 and cc3) and timing to complete synchronous divisions s1, s2, and s3 were calculated. The KIDScore ranking was recorded. Main results and the role of chance Embryos resulting in biochemical pregnancy behaved similarly to those embryos resulting in a clinical pregnancy in terms of tPNa, tPNf, t2, t3, t4, t5, t6, t7, t8, tM, tsB, cc2, cc3, s1, s3 and KIDScore ranking, but tended to present slower tB (p = 0.089) and s2 (p = 0.084). Embryos resulting in a negative pregnancy showed significantly slower embryo development in terms of tPNa, tPNf, t2, t3, t4, cc2, and KIDScore ranking compared to both Biochemical and Positive groups and differed from the Positive group only in terms of t6, t7, t8, s1, s2, and s3. Limitations, reasons for caution The use of historical cohort groups is a drawback. Despite the eligibility criteria for inclusion in the analysis, potential differences in the baseline characteristics cannot be ruled out. Wider implications of the findings Biochemical pregnancy is likely multifactorial, including both embryo and endometrial factors. Further research is needed to identify factors that can predict and prevent biochemical pregnancy. Trial registration number N/A