Does the cell number of 0PN embryos on day 3 affect pregnancy and neonatal outcomes following single blastocyst transfer?

BACKGROUND: 0PN zygotes have a low cleavage rate, and the clinical outcomes of cleavage-stage embryo transfers are unsatisfactory. Blastocyst culturing is used to screen 0PN embryos, but whether the cell number of 0PN embryos on day 3 affects the clinical outcomes following single blastocyst transfer is unknown and would be helpful in evaluating the clinical value of these embryos. METHODS: This retrospective study compared 46,804 0PN zygotes, 242 0PN frozen-thawed single blastocyst transfers, and 92 corresponding 0PN singletons with 232,441 2PN zygotes, 3563 2PN frozen-thawed single blastocyst transfers, and 1250 2PN singletons from January 2015 to October 2019 at a tertiary-care academic medical centre. The 0PN and 2PN embryos were divided into two groups: the group with < 6 cells on day 3 and that with ≥ 6 cells. Embryo development, subsequent pregnancy and neonatal outcomes were compared between the two groups. RESULTS: The cleavage and available blastocyst rates of the 0PN zygotes were much lower than those of the 2PN zygotes (25.9% vs. 97.4%, P < 0.001; 13.9% vs. 23.4%, P < 0.001). In the < 6 cells group, the available blastocyst rate of the cleaved 0PN embryos was significantly lower than that of the 2PN embryos (2.5% vs. 12.7%, P < 0.001). However, in the ≥ 6 cells group, the available blastocyst rate of the 0PN cleaved embryos significantly improved, although it was slightly lower than that of the 2PN embryos (33.9% vs. 35.7%, P = 0.014). Importantly, compared to those of the 2PN single blastocyst transfers, the clinical pregnancy rate, live birth rate, Z-score and malformation rate of the 0PN single blastocyst transfers were not significantly different in either the < 6 cells group (30.4% vs. 39.8%, P = 0.362; 30.4% vs. 31.3%, P = 0.932; 0.89 ± 0.90 vs. 0.42 ± 1.02, P = 0.161; 0% vs. 2.6%, P = 1.000) or the ≥ 6 cells group (50.7% vs. 46.6%, P = 0.246; 39.7% vs. 38.3%, P = 0.677; 0.50 ± 1.23 vs. 0.47 ± 1.11, P = 0.861; 2.4% vs. 1.8%, P = 1.000). CONCLUSIONS: The cell number on day 3 of 0PN embryos affected the subsequent formation of blastocysts but did not influence the subsequent pregnancy and neonatal outcomes of 0PN single blastocyst transfers, which may be beneficial to clinicians counselling patients on the clinical value of 0PN embryos.

Live births resulting from 0PN-derived embryos in conventional IVF cycles.

PURPOSE: The aim of this study was to (1) investigate the incidence of embryos derived from "unfertilized oocytes" i.e., oocytes not displaying pronuclei (0PN) at the time of the fertilization check and (2) determine the clinical pregnancy rates when transferring 0PN-derived embryos. METHODS: In this retrospective study, 4424 IVF-ET cycles were reviewed. RESULTS: In total, 11.3% (4966/43,949) 0PN-derived embryos were observed. It was found that female age, number of oocytes, and the top-quality embryo rate were significantly correlated with 0PN-derived embryo occurrence. The source of embryos transferred did not impact significantly on clinical pregnancy and live-birth rates. Of the 183 cycles included in this study where 275 0PN-derived embryos were transferred in total, only 0PN-derived embryos were available in 70 of those cycles. It was noteworthy that 13 healthy infants resulted from 0PN-derived embryos with an implantation rate of 17.0%. CONCLUSION: These results indicate that the traditional method of excluding embryos because of those oocytes originally lacking any sign of a pronucleus at the fertilization check should be re-considered as transferring 0PN-derived embryos with subsequent expected developmental performance may be considered as an option for those patients where no other embryos are available.

Developmental potential of non- and mono-pronuclear zygotes and associated clinical outcomes in IVF cycles.

Purpose: This study aims to evaluate the developmental potential of 0PN, 1PN, and 2PN zygotes in IVF cycles and compare their clinical outcomes. Methods: We conducted a retrospective cohort study involving IVF patients. Blastocyst formation rates were assessed with 0PN, 1PN, and 2PN zygotes. Subsequently, we collected clinical outcome data following the transfer of these zygotes. Results: The overall blastulation rate was similar between 0PN (29.6%) and 2PN (32.1%) zygotes, but 1PN zygotes exhibited a significantly lower blastulation rate (17.0%) compared to both 0PN and 2PN zygotes. Similarly, the overall rate of good-quality blastulation was comparable between 0PN (15.3%) and 2PN (17.5%) zygotes, while 1PN zygotes showed a significantly lower rate (7.0%) compared to both 0PN and 2PN. Clinical pregnancy, ectopic pregnancy, implantation, and live birth rates were similar among single blastocyst frozen embryo transfers (FET) of 0PN, 1PN, and 2PN. Additionally, no significant differences were observed between single- and double-blastocyst FET of 0PN and 2PN. Conclusions: Our findings suggest that 0PN and 2PN zygotes have comparable developmental potential, while 1PN embryos exhibit lower developmental potential. Blastocyst FET outcomes appear similar among 0PN, 1PN, and 2PN zygotes.

The aneuploidy testing of blastocysts developing from 0PN and 1PN zygotes in conventional IVF through TE-biopsy PGT-A and minimally invasive PGT-A.

Zygotes without a pronuclear (0PN) or with one pronuclear (1PN) were defined as abnormal fertilization in conventional in vitro fertilization (IVF). The removal of 0PN and 1PN zygotes from conventional IVF cycles has always been controversial. This study aimed to investigate the chromosomal aneuploidy rates of 0PN- and 1PN-derived blastocysts in conventional IVF cycles and to assess the concordance rate between TE-biopsy PGT-A and miPGT-A. TE biopsies and culture media with blastocoel fluid (CM-BF) samples were whole-genome amplified by multiple annealing and looping-based amplification cycle-based single-cell ChromInst method. Next generation sequencing was performed for comprehensive chromosomal screening on a NextSeq550 sequencer using the NextSeq 500/550 High Output kit v2. The aneuploidy rates of 0PN-derived blastocysts were 19.7% for TE-biopsy PGT-A, and 36.1% for miPGT-A; the concordance rate for ploidy was 77.0%; and the sensitivity and specificity were 83.3% and 75.5%, respectively. The aneuploidy rates of 1PN-derived blastocysts were 37.5% and 37.5% by TE-biopsy PGT-A and miPGT-A, respectively; the concordance rate between TE biopsies and CM-BF samples was 83.3%; and the sensitivity and specificity were 77.8% and 86.7%, respectively. Regarding TE-biopsy PGT-A, there were no significant differences in aneuploidy rates among 0PN-, 1PN- and 2PN-derived blastocysts (PGT-M cycles) (19.7% vs. 37.5% vs. 24.3%, P = 0.226), but the aneuploidy rate of 1PN-derived blastocysts was slightly higher than the other two groups. An increase in aneuploidy rates was observed for 0PN/1PN-derived day 6 blastocysts compared to 0PN/1PN-derived day 5 blastocysts (TE-biopsy PGT-A: 35.7% vs. 19.3%, P = 0.099; miPGT-A: 39.3% vs. 35.1%, P = 0.705). The present study is the first that contributes to understanding the chromosomal aneuploidies in 0PN- and 1PN-derived blastocysts in conventional IVF cycles using TE-biopsy PGT-A and miPGT-A. The clinical application value of 0PN- and 1PN-derived blastocysts in conventional IVF should be assessed using TE-biopsy PGT-A or miPGT-A due to the existence of chromosomal aneuploidies.. In terms of consistency, the miPGT-A using blastocoel fluid enriched culture medium is promising as an alternative to TE-biopsy PGT-A for aneuploidy testing of 0PN- or 1PN-derived blastocysts in conventional IVF.

Development and frozen-thawed transfer of non-pronuclear zygotes-derived embryos in IVF cycles.

OBJECTIVE: To explore the development and pregnancy potential of non-pronuclear (0PN) zygote-derived embryos in conventional in vitro fertilization (IVF) cycles. STUDY DESIGN: Embryonic development in 1039 oocyte retrieval cycles and clinical outcomes of 659 frozen-thawed blastocyst transfer cycles were retrospectively studied. RESULTS: Developmental potential of embryos with different blastomere numbers on day 3 were inconsistent in 0PN and 2PN groups. For 0PN-derived embryos, blastocyst rate of fast developing embryos (75.4%) was similar to that of intermediately developing embryos (72.9%), but good quality blastocyst rate of the former (49.2%) was significantly higher than that of the later (39.6%). In 2PN group, intermediately developing embryos had the highest blastocyst rate (77.9%) and good quality blastocyst rate (51.5%) (statistically significant). Comparison of frozen-thawed transfer was carried out between 0PN- and 2PN-derived blastocysts. For both single (SBT) and double blastocyst transfer (DBT) groups, no statistical differences existed between 0PN- and 2PN-derived blastocysts in clinical pregnancy rates (45.2% and 49.1% in SBT group, 64.7% and 66.4% in DBT group), implantation rates (45.2% and 49.1% in SBT group, 41.2% and 47.7% in DBT group) and live birth rates (35.5% and 36.8% in SBT group, 52.9% and 51.2% in DBT group). CONCLUSION: The developmental characteristic of 0PN-derived embryos was different from that of 2PN-derived embryos in IVF cycles. 0PN-derived blastocysts could obtain acceptable clinical pregnancy and live birth, but more studies are needed to confirm the safety..

Blastocysts Derived From 0PN Oocytes: Genetic And Clinical Results.

OBJECTIVE: To analyze the genetic and clinical outcomes of blastocysts derived from 0PN oocytes after IVF/ICSI. METHODS: This retrospective observational study included patients aged 40 years or younger submitted to IVF/ICSI with their own oocytes and with blastocysts derived from 0PN oocytes between January 2015 and April 2018. The clinical outcomes of 0PN blastocyst transfers were analyzed. Genetic tests were performed on biopsied 0PN blastocysts with Next Generation Sequencing. RESULTS: A total of 27 0PN blastocysts were transferred, yielding an implantation rate of 48.0% and an ongoing pregnancy rate of 50.0%. The transfers resulted in 13 live births (59.0% live birth rate). Genetic test results revealed that four of the 17 0PN blastocysts biopsied were 46XX; three were 46XY; and 10 were aneuploid embryos, awarding a diploid rate to 76.4% (13/17). CONCLUSION: Almost half of the 0PN blastocysts implanted (48.0%) and 13 healthy babies were born. More than three quarters (76.4%) of the 0PN blastocysts were diploid, thus ruling out the possibility of parthenogenetic activation. Our study indicated that the transfer of 0PN blastocysts is a safe, worthy option when the number of normal 2PN embryos is insufficient.

Value of transferring embryos that show no evidence of fertilization at the time of fertilization assessment.

OBJECTIVE: To determine the value of transferring embryos formed from nonpronuclear (0PN) zygotes. DESIGN: A case-control study. SETTING: Not applicable. PATIENT(S): The current study was a retrospective analysis of embryo transfers of just 0PN embryos using fresh cleavage-stage embryos (0PN cleavage fresh), frozen-thawed cleavage-stage 0PN embryos (0PN cleavage frozen), and frozen 0PN blastocyst-stage embryos (0PN blast frozen). INTERVENTION(S): To study the effect of 0PN transfer, comparison groups were used: fresh cycles of 2PN (2PN cleavage fresh-C) and frozen-thawed cycles cleavage-stage (2PN cleavage frozen-C) and blastocyst-stage (2PN blast frozen-C). Comparison groups were matched for cycle and patient characteristics to the 0PN group. MAIN OUTCOME MEASURE(S): Implantation rate (IR), pregnancy rate, and transferable embryo rate. RESULT(S): For fresh cycles, the IR in the 0PN cleavage fresh was lower than that in the 2PN cleavage fresh-C (8.04% vs. 19.50%, respectively). For frozen-thawed cycles, the IR in the 0PN cleavage frozen was lower than that in the 2PN cleavage frozen-C (15.38% vs. 28.24%, respectively), but the IR in 0PN blast frozen was comparable to that of 2PN blast frozen-C (39.56% vs. 48.18%, respectively). CONCLUSION(S): Transfer of 0PN embryos from fresh or frozen-thawed cycles results in pregnancies and live births. Nonpronuclear embryos have a lower IR than 2PN embryos, but if the embryos are cultured to the blastocyst stage and then are frozen, their IRs approach that of 2PN embryos in subsequent frozen-thawed cycles. The culture of 0PN embryos to the blastocyst stage may select for embryos with a near-normal IR.