Multinucleation in the early human cleavage-stage embryo in vitro is associated with reduced pregnancy rate and an increased number of abortions

Purpose Blastomere multinucleation of cleavage-stage embryos is defined as the presence of more than one visible nucleus per blastomere at a given time point during early embryonic development in vitro. Multinucleation has been associated with decreased blastulation and implantation rates following ART-treatments. Here we investigate early embryonic multinucleation assessed utilizing the EmbryoScope^TM time-lapse monitoring system (TMS) and its effect on ongoing pregnancy rates in our IVF-program.

Material and Methods In a retrospective observational study multinucleation at ESHRE / ALPHA consensus-proposed embryo evaluating times was detected in cleavage-stage embryos with our TMS. Transfers were grouped according to the percentage of multinucleated blastomeres during 2-cell-stage (50 % vs. 100 %); transfers without multinucleated embryos served as controls.

Results Multinucleation was detected in 384 of 1804 embryos designated for transfer in 1062 IVF / ICSI cycles. In double-embryo-transfers patients with multinucleated embryos displayed a significantly lower pregnancy rate (35.2 % vs. 48.4 %, p = 0.0076) and higher abortion rate (40.5 % vs. 25.7 %, p = 0.0003) compared to controls. The same effect was observed in single-embryo-transfers (pregnancy-rate: 10.8 % vs. 27.2 %, p = 0.0004)

Conclusion Blastomere nuclear formation is a dynamic process and the occurrence of multinucleation in 2-cell-stage human embryos seems to have a profound effect on implantation and ongoing pregnancy rate. Monitoring this parameter with a TMS for non-invasive pre-selection of embryos with lower developmental potential offers a clear advantage over conventional assessment of embryo morphology at given time points. Excluding multinucleated embryos from transfer were possible may also allow for decreased abortion rates.

Publication History

Article published online:
07 October 2020