Limited importance of pre-embryo pronuclear morphology (zygote score) in assisted reproduction outcome in the absence of embryo cryopreservation

Biological predictive criteria for clinical pregnancy after elective single embryo transfer

“…Indeed, Z1-Z2-derived embryos would have a higher ability to implant compared with Z3-Z4 zygotes (26). However, conclusions about the relevance of zygotic morphology to identify embryos with high implantation potential are still unclear, because some authors reported increased CPR (27) whereas others did not (28,29). Moreover, although it is currently recommended to preferentially select early cleaved embryos for ET, our data failed to show any relationship between early cleavage and the onset of pregnancy, as previously reported in patients eligible for eSET by Thurin et al (19) and recently confirmed (30).…”

Predictive value of embryo grading for embryos with known outcomes

“…In spite of multiple advances in the field of advanced reproductive technologies (ART), the efficiency of IVF remains low, with <30% of all embryos transferred resulting in a clinical pregnancy (1)(2)(3). This low rate leads to the practice of transferring multiple embryos to achieve a good pregnancy rate; however, this practice then leads to an undesirable rate of multiple gestations.…”

Embryo quality but not pronuclear score is associated with clinical pregnancy following IVF

“…Cell number and embryo grade are more predictive of implantation rate than PN morphology in a study of 852 embryos when all or none of the embryos implanted [18]. Nicoli et al, 2007 found that 1,078 PN-scored embryos showed no relationship between PN patterns and embryo quality or clinical pregnancy [27]. A smaller study of 331 embryos which were also biopsied, reported no association between PN pattern, embryo quality or chromosome status [28].…”