Cell Number on Day 3 of Embryo Development is Associated with Ploidy and Pregnancy Rates
Selection of a blastocyst for transfer is based on day5/6 morphology with day3 morphology only used if two blastocysts are equal in quality. Day3 assessments are based on cell number and fragmentation with embryos that are developmentally advanced ([Formula: see text]10 cells) being downgraded. Afte...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
World Scientific Publishing
2022-09-01
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| Series: | Fertility & Reproduction |
| Online Access: | https://www.worldscientific.com/doi/10.1142/S2661318222741121 |
| Summary: | Selection of a blastocyst for transfer is based on day5/6 morphology with day3 morphology only used if two blastocysts are equal in quality. Day3 assessments are based on cell number and fragmentation with embryos that are developmentally advanced ([Formula: see text]10 cells) being downgraded. After extended development, if [Formula: see text]10 cell embryos are the best quality they are selected for transfer. Thus, the aim of this study was to determine if cell number on day3 has an impact on embryo fate, euploidy rates and pregnancy rates. Data was retrospectively analysed from 269 women (average age 35.7) undergoing stimulated IVF treatment. Embryos were allocated to one of four categories based on day3 morphological score [Formula: see text]6 cells, 7-9 cells, 10-12 cells and [Formula: see text]13 cells. Results were correlated with embryo fate (vitrification/transfer) and pregnancy rates. After extended culture embryos with [Formula: see text]13 cells on day 3 were mostly likely to have undergone a fresh transfer (28.1%, p[Formula: see text]0.05) compared with embryos with 7-9 cells and 10-12 cells (13.7% and 14.0%, respectively). Embryos with [Formula: see text]6 cells were least likely to be transferred (5.2%) and vitrified (7.1%). Further, embryos with [Formula: see text]6 cells had the lowest pregnancy rate (12.5%) compared with all other groups (p[Formula: see text]0.05). No differences were observed for embryos with 7-9 cells, 10-12 cells and [Formula: see text]13 cells for vitrification rates (42.3%, 40.5% and 35.1%, respectively) or pregnancy rates (33.5%, 43.5% and 45.8%, respectively). Interestingly, the incidence of euploid embryos was increased in [Formula: see text]13 cell embryos (70.0%, p[Formula: see text]0.05) compared with [Formula: see text]6 cells, 7-9 cells and 10-12 cells (52.0%, 42.6% and 52.5%, respectively). Results from this study provide evidence that a review on cleavage stage embryo grading protocols which currently downgrades developmentally advanced embryos [Formula: see text]10 cells is warranted as these embryos do not appear to have a negative impact on pregnancy rates and can result in some of the best clinical outcomes. |
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| ISSN: | 2661-3182 2661-3174 |