Impact of multinucleated blastomeres on embryo developmental competence, morphokinetics, and aneuploidy

Objective: To study the effect of human embryo multinucleation on the rate of aneuploidy, in vitro developmental morphokinetics, and pregnancy outcome. Design: Retrospective study. Setting: University-affiliated fertility center. Patient(s): A total of 296 patients undergoing IVF cycles. Intervention(s): None. Main Outcome Measure(s): Rate of multinucleation at the 2- and 4-cell stage, time-lapse morphokinetic parameters from zygote to blastocyst stage, ploidy of embryos analyzed by means of trophectoderm biopsy and array comparative genomic hybridization (PGS), and pregnancy outcome. Result(s): A total of 1,055 out of 2,441 (43.2%) embryos evaluated with the use of the Embryoscope time-lapse system showed blastomere multinucleation at the 2- cell stage (MN2). The frequency of this abnormality was substantially reduced in 4-cell-embryos (15.0%). Among all clinical factors analyzed, only maternal age had a positive correlation with multinucleation rate. The timing of cleavage divisions from the pronuclear fading to 5-cell embryo was significantly longer (1.0-2.5 h) in MN2 embryos than in non-MN2 control samples. Of the total embryos tested with the use of PGS (n = 607), the rates of multinucleation were similar in euploid versus aneuploid blastocysts (40.8% and 46.7%, respectively). All 24 chromosomes contributed to aneuploidy of MN2 embryos. There were 61 transfers of MN2 embryos that resulted in 45.9% clinical pregnancies and a 31.6% implantation rate. Conclusion(s): The frequency of multinucleation is high in human embryos cultured in vitro and equally affects euploid and aneuploid human embryos. It appears thatmostMNembryos have the capacity for self-correction during early cleavage divisions and can develop into euploid blastocysts resulting in healthy babies. ((C) 2016 by American Society for Reproductive Medicine.)