Factors associated with birth outcomes from cryopreserved blastocysts: experience from 4,597 autologous transfers of 7,597 cryopreserved blastocysts (original) (raw)
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Frozen-thawed embryo transfer cycles: clinical outcomes of single and double blastocyst transfers
Journal of Assisted Reproduction and Genetics, 2011
Purpose To evaluate clinical outcomes of frozen-thawed embryo transfer cycles when one or two blastocysts are transferred. Methods Retrospective chart review Results Two hundred forty-three frozen blastocyst transfer (FBT) cycles were analyzed. Clinical pregnancy rate (50.4% vs. 34.7%), live birth rate (45.8% vs. 30.6%), and twin live birth rate (19.3% vs. 0) were significantly higher in the double versus single FBT group, respectively (p<0.05). Prior fresh cycle success with same-cohort embryos did not predict outcome of FBT cycle. When the fresh cycle was unsuccessful, there still was a significant increase in twinning when two frozen-thawed blastocysts were transferred. Conclusions Transferring two blastocysts during an FBT cycle resulted in higher live birth and twin live birth rates. Single FBT provided acceptable pregnancy rates for couples seeking to avoid a multiple pregnancy or for those having a single blastocyst stored. Interestingly, the outcome of fresh cycle with same-cohort embryos did not influence the outcome of frozen-thawed cycle.
A prospective evaluation of cryopreservation strategies in a two-embryo transfer programme
Human Reproduction, 1997
the elective embryo cryopreservation of all embryos and the 2 To whom correspondence should be addressed transfer of thawed embryos in subsequent cycles (Wada et al., 1992, 1993; Pattinson et al., 1994); (iv) in a donor oocyte A total of 364 consecutive patients requesting in-vitro programme, enabling a second human immunodeficiency virus fertilization (IVF) treatment were divided randomly into antibody test to be performed on the oocyte donor 6 months two groups. In the first group, two embryos in the original later, before the embryos are released from 'quarantine' for IVF cycle were allowed to divide prior to transfer, with any replacement (Hamer et al., 1994); and (v) prior to chemotherapy remaining embryos being cryopreserved at the pronucleate as a means of preserving the patient's future fertility potential (PN) stage. In the second group, all the embryos were (Winkel and Fossum, 1993; Brown et al., 1996). allowed to divide to the early cleavage (EC) stage, and the The use of embryo cryopreservation by IVF units is increasbest two replaced; any suitable remaining embryos were ing rapidly, such that in 1989~700 pregnancies had been frozen at the 2-to 4-cell stage. A total of 134 cycles (36.8%) achieved worldwide (Van Steirteghem and Van Den Abbeel, fulfilled the study criteria for a fresh embryo replacement 1990). Indeed, in 1993 in the UK alone, Ͼ764 live births were and supernumerary embryos cryopreserved. In the PN reported from 6004 frozen-thawed embryo transfers (Human group, 72 out of 182 (39.6%) patients had a fresh embryo Fertilization and Embryology Authority, 1995). replacement accompanied by embryo cryopreservation, The cryopreservation of good quality embryos is generally which was not significantly different from the EC group regarded as being of paramount importance for optimum (62/182; 34.1%). The livebirth rate per fresh embryo embryo survival (Cohen et al., 1986; Mandelbaum et al., transfer in the EC group (17/62; 27.4%) was significantly 1987). However, the stage at which embryos are cryopreserved higher than that for the PN group (8/72; 11.1%; P Ͻ 0.05). varies from clinic to clinic: freezing embryos at the pronuclear Embryo survival following thawing was similar for the PN (PN; Testart et al., 1987; Cohen et al., 1988a,b; Fugger et al., (96/129; 74.4%) and EC (79/102; 77.4%) stages. Although 1988), early cleavage (EC; Lassalle et al., 1985; Freeman not significant, the livebirth rate following the transfer of et al., 1986; Friedler et al., 1988) or blastocyst (Fehilly et al., thawed embryos was higher in the PN group (11/44; 25.0%) 1985) stage all result in a large proportion of the embryos than in the EC group (4/38; 10.5%). Following one fresh surviving the rigours of the freeze-thaw process, and have and two freeze-thaw embryo replacements, the observed resulted in live births. The cryoprotectant used in conjunction cumulative viable pregnancy rates were comparable for with freezing is also stage-specific, with propanediol (PROH; patients in both the PN (40.2%) and EC (41.1%) groups. Mohr and Trounson, 1985), dimethylsulphoxide (DMSO; Key words: cryopreservation/embryo/human Cohen et al., 1985b) or glycerol (Troup et al., 1990) being used for the PN, EC and blastocyst stages respectively of embryo development. Embryos can be frozen in vials, straws
Human Reproduction, 2010
background: There are conflicting results on whether the rate of blastocyst development before freezing influences the outcome of frozen-thawed blastocyst transfers. methods: We conducted a systematic review and meta-analysis of controlled studies to compare pregnancy outcomes following transfer of thawed blastocysts that were frozen either on Day 5 or Day 6 following fertilization in vitro. Searches were conducted on MEDLINE, EMBASE, Cochrane Library and Web of Science. Study selection and data extraction were conducted independently by two reviewers. The Newcastle-Ottawa Quality Assessment Scale was used for quality assessment. results: We identified 15 controlled studies comprising 2502 frozen-thawed transfers involving blastocysts that were either frozen on Day 5 or Day 6. Meta-analysis of these studies showed significantly higher clinical pregnancy rate [relative risk (RR) ¼ 1.14, 95% confidence interval (CI): 1.03 -1.26, P ¼ 0.01] and ongoing pregnancy/live birth rate (RR ¼ 1.15, 95% CI: 1.01-1.30, P ¼ 0.03) with Day 5 compared with Day 6 frozen-thawed blastocyst transfers. Sensitivity analysis of those studies where blastocysts frozen on Day 5 or Day 6 were at the same stage of development showed no significant difference in the clinical pregnancy rate (RR ¼ 1.07, 95% CI: 0.87 -1.33, P ¼ 0.51) and ongoing pregnancy/live birth rate (RR ¼ 1.08, 95% CI: 0.92 -1.27, P ¼ 0.36).
Human reproduction (Oxford, England), 2018
The aim of this study was to evaluate the live birth rate (LBR) after frozen-thawed Day 5 (D5) and Day 6 (D6) blastocyst transfers. LBR following frozen-thawed blastocyst transfer is significantly lower with D6 than with D5 blastocyst regardless of embryo quality. During fresh embryo transfer cycles, pregnancy rates (PR) are significantly higher when transferring blastocysts expanded on D5 compared with slow developing blastocysts (D6). In programmed thawed blastocyst transfer (TBT) cycles, the same clinical outcomes should be expected when transferring D5 or D6 blastocysts because of endometrial/embryonic synchronization due to hormonal priming of endometrial receptivity. However, the impact of delayed blastocyst expansion at D6 on clinical outcomes remains unclear. Some reports have shown higher PRs after D5 TBT compared with those of D6, while others have shown equivalent TBT outcomes after D5 and D6 cryopreserved blastocysts transfers. This retrospective cohort follow-up study i...
Embryonic factors affecting outcome from single cryopreserved embryo transfer
Reproductive BioMedicine Online, 2007
Multiple pregnancy minimization by single embryo transfer is becoming more prevalent, but is less common in the case of cryopreserved embryos. This study defi nes embryonic characteristics in single cryopreserved embryo transfers associated with success rates equivalent to those achieved when transferring two cryopreserved embryos. In a retrospective analysis of 6916 cryopreserved day-2 embryo transfer procedures, transfer of two cryopreserved embryos resulted in higher clinical pregnancy rates when compared with transfer of a single thawed embryo but was also associated with elevated multiple pregnancy rates (26.7% in women under 36). Optimal outcome (implantation rate of 30.9%) from single cryopreserved embryo transfer (SCET) in women under 36 was associated with cryopreservation at the 4-cell stage, loss of fewer than two blastomeres and subsequent cleavage of at least two surviving blastomeres. In comparison, transfer of two cryopreserved embryos in women under 36 resulted in pregnancy and implantation rates of 25.5 and 16.1% respectively. Interestingly, in cryopreserved 4-cell stage embryos, loss of a single blastomere did not reduce implantation potential and cleavage of only a single post-thaw blastomere was not indicative of increased implantation potential. Establishment of these critical thresholds provides a rational basis for SCET.
JBRA assisted reproduction, 2022
Objective: Advances in embryo culture conditions and the development of vitrification as a revolutionary cryopreservation method have allowed for routine use of blastocyst transfer in assisted reproduction technology (ART) cycles. Several vitrification/warming media and devices have been introduced for commercial use so far. The aim of this retrospective study was to compare postwarming survival rates and clinical outcomes of human blastocysts vitrified/warmed by two different commercial methods (CryoTouch and Cryotop) during ART cycles. Methods: This retrospective study assessed a total of 50 frozen embryo transfer (FET) cycles conducted on 56 warmed blastocysts between January 2018 and December 2020. Post-warming blastocyst survival rates and clinical outcomes including clinical pregnancy and live birth rates were calculated after single blastocyst transfer cycles. Results: The results revealed no significant differences between two groups in post-warming survival rate (p-value=0.8381), clinical pregnancy rate (p-value=0.8157) and live birth rate (p-value=0.7041). Conclusions: Post-warming survival rates and clinical outcomes were comparable with no significant difference in blastocysts vitrified/warmed by CryoTouch and Cryotop commercial methods.
Journal of Assisted Reproduction and Genetics, 2004
Purpose : To compare the effects of two different blastocyst thawing protocols on implantation, pregnancy, and live birth rates. Methods : Ninety four consecutive frozen-thawed blastocyst transfers from 1996 to 2002 were retrospectively analyzed. Blastocysts were cryopreserved using Menezo's two-step slowfreezing protocol. Frozen blastocysts were thawed for transfer according to Menezo's stepwise or two-step protocol. Immediately after thawing, assisted hatching was performed and all embryos were cultured for 3 to 5 h before transfer. Only viable embryos were selected for transfer. Results : Implantation, pregnancy (determined by the presence of fetal cardiac activity), and live birth rates were significantly higher with two-step (25, 45.7, and 42.9%) than with stepwise thawing protocol (9.2, 18.6, and 16.9%, P < 0.01). The percentage of gestational sacs resulting in live babies was higher with two-step thawing (76.6%) than with stepwise thawing (50%, P = 0.04). Conclusions : We conclude that the two-step thawing protocol offers advantages over the stepwise method. The two-step thawing protocol dramatically increased embryo implantation potential, resulting in higher pregnancy rate, and subsequent live birth rate, after frozen blastocyst transfer.
Journal of Clinical Medicine
The frozen embryo transfer (FET) technique has been progressively used more worldwide due to improved culture conditions, as well as enhanced survival rates after vitrification. However, little is known about the effect of the post-thaw blastocyst culture duration prior to transfer on live birth rate in FET cycles. In this retrospective observational study, we evaluated the influence of two distinct post-thaw blastocyst culture spans (2–4 h versus 20–22 h) on clinical pregnancy and live birth rate. A total of n = 1927 frozen–warmed cycles were included in the analysis. Among those, n = 885 warmed blastocysts were cultured for 2–4 h, and n = 1029 were kept in culture for 20–22 h prior to transfer; the remaining blastocysts did not survive the warming protocol. We observed no significant differences in live birth and clinical pregnancy rates between the two groups. The blastocyst morphological evaluation at transfer improved following the longer culture time. No differences between th...
Reproductive BioMedicine Online, 2009
Although several early IVF successes were achieved after transferring fully formed blastocysts, the majority of embryos replaced worldwide over the past 30 years have been at the cleavage stage. The programme at this study centre has previously found that delaying an embryo transfer to day 5 can reduce the chance for a high-order multiple gestation without compromising the pregnancy rate because fewer embryos can be replaced. To evaluate the impact of transfer day and embryonic stage at cryopreservation on cycle outcome, 6069 fresh and 706 frozen transfers from 2000-2006 performed at this study centre were retrospectively analysed. Approximately half of the fresh transfers were performed on day 3, with a shift to day-5 transfer over the study period with no change in cryopreservation incidence. Implantation, clinical pregnancy and live birth rates were significantly higher following day-5 transfer. When frozen-thawed embryos (2-cell to day-6 blastocysts) were transferred, acceptable pregnancy and live birth rates were achieved at all stages but thawed embryos transferred as day-5 blastocysts generated consistently higher clinical pregnancy and live birth rates. Transfer of embryos frozen on day 6 had the highest miscarriage and lowest live birth rates. Barring government regulation, an IVF programme&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;#39;s day for cryopreservation generally depends on its management of and success with fresh embryo transfer.