Embryo fragmentation – Is it really a detrimental factor?

Abstract Purpose: To learn what is the implantation potential of fragmented embryos that underwent morphokinetic evaluation in a time-lapse incubator. Methods: A retrospective study analyzing 4,210 Day 5 embryos incubated in a time-lapse incubator, between 2013 and 2019. Fragmentation was measured by using the software tools. Embryos selected using the general model and re-examined by our in-house model. Embryos with more than 5% fragmentation (379 embryos) were included in the study. Embryo fragmentation percentage was documented from the first cell division (start fragmentation) to its maximal percentage (final fragmentation), and the ratio between them (fragmentation worsening). Data was analyzed with relation to embryo development, morphokinetics, embryos transfer or freezing, clinical pregnancy and live birth rates. Results: Embryo fragmentation and morphokinetics were found to be independent variables for clinical pregnancy achievements. A higher fragmentation worsening was noted among discarded embryos compared to transferred or frozen embryos (p<0.0001). Advanced maternal age had a significant negative effect on fragmentation (p<0.001). Missed abortion rates were similar in fragmented embryos that implanted compared with the overall population. Live birth rates were comparable among embryos with different severity of fragmentation. Conclusion: Our study shows that fragmented embryos have a potential to implant and therefore should be selected for transfer. Laboratories which do not use time-lapse incubators for embryo selection, should consider transferring fragmented embryos, since they have an acceptable chance for live birth. Embryo evaluation for fragmentation and the calculation of fragmentation worsening may enhance our ability to predict embryo development and lead to decreased embryo wastage.