Early cleavage of in-vitro fertilized human embryos to the 2-cell stage: a novel indicator of embryo quality and viability

Abstract

A number of non-invasive methods have been proposed to evaluate embryo viability in human in-vitro fertilization programmes. In addition to biochemical analyses, a common method for the selection of embryos prior to transfer involves assessment of embryo quality and morphology. We propose a new method to evaluate embryo viability based on the timing of the first cell division. Fertilized embryos that had cleaved to the 2-cell stage 25 h post-insemination were designated as 'early cleavage' embryos while the others that had not yet reached the 2-cell stage were designated as 'no early cleavage'. In all cases the early cleavage embryos were transferred when available. Early cleavage was observed in 27 (18.9%) of the 143 cycles assessed. There were significantly (chi2 = 4.0; P = 0.04) more clinical pregnancies in the early cleavage group, 9/27 (33.3%), compared with the no early cleavage group, 17/116 (14.7%). No difference was found when comparing key parameters (age, stimulation protocol and semen characteristics) of couples belonging to both groups, pointing to an intrinsic property or factor(s) within the early cleaving embryos. We propose 'early cleavage' as a simple and effective non-invasive method for selection and evaluation of embryos prior to transfer.

Live birth following transfer of a cryopreserved embryo generated from a cryopreserved oocyte and a cryopreserved sperm: Case report

“…Such restrictions inevitably result in the loss of the ability to apply selective criteria when choosing embryos for transfer. Criteria such as morphology and cleavage rate [13], and timing of the first cleavage division [14][15][16] have been applied succesfully to select early cleavage stage embryos with enhanced implantation potential for transfer. This approach is only realistically feasible, however, when it is possible to cryopreserve the remaining embryos in a cohort which are not chosen for transfer.…”

Evaluation of the safety of time-lapse observations for human embryos

“…For these reasons, many criteria for embryo selection have been proposed in the field of assisted reproductive technology (ART) [1][2][3][4][5][6][7]. Among of these criteria, morphologic features have been used extensively in selecting good-quality embryos.…”

Selection of Embryos for Day-3 Transfer at the Pronuclear-Stage and Pronuclear-Stage Cryopreservation Results in High Delivery Rates in Fresh and Frozen Cycles

“…Several oocyte, zygote, and cleavage-stage grading methods that were not used in this study have been shown to correlate with an embryo's implantation potential (1)(2)(3)(5)(6)(7)11,12,28,(30)(31)(32)(33)(34)(35)(36)(37). Tesarik et al (1) showed that the relationship between the number of embryos transferred and the multiple rate depended on PN-S morphology; transfer of 2 embryos from pattern zero zygotes usually resulted in a twin pregnancy.…”

“…New methods under evaluation include number, pattern, and distribution of nucleoli within the PN (1,2,5,7), size and shape of PN-S halos (7), early cleavage to the 2-cell stage (32,36,37), day-3 fragmentation pattern (35), and variation in the thickness of the zona pellucida.…”