Trial reportJournal of assisted reproduction and genetics2018
Increased live births after day 5 versus day 6 transfers of vitrified-warmed blastocysts.
Trial report in Journal of assisted reproduction and genetics, 2018. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 25 papers, 2 of them syntheses that pooled it.
What it found
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The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.
The trial behind it
Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.
Neither the registry nor the abstract names a trial number. If this is a trial report, that itself is worth knowing.
Who cites it
25 citing papers in PubMed, 2 syntheses or guidelines pooled it.
- Pregnancy and perinatal outcomes after day 5 versus day 6 blastocyst-stage embryo transfer: A systematic review and meta-analysis.Acta obstetricia et gynecologica Scandinavica · 2026Pooled it
- Day 5 versus Day 6 blastocyst transfers: a systematic review and meta-analysis of clinical outcomes.Human reproduction (Oxford, England) · 2019Pooled it
- Day 6 vitrified blastocyst transfer on day 5 vs. day 6 of progesterone shows similar outcomes in HRT-FET cycles: a cohort study.Scientific reports · 2025Article
- Delayed blastocyst development is associated with altered metabolism and proteome in male and female bovine embryos†.Biology of reproduction · 2025Article
- Evaluation of day 5 versus day 6 blastocyst biopsy in preimplantation genetic testing: clinical and neonatal outcomes.Frontiers in endocrinology · 2025Article
- Effects of Various Transfer Strategies of Frozen-Thawed Cleavage-Stage and Blastocyst Embryos on Pregnancy and Neonatal Outcomes in Different Age Groups.Journal of multidisciplinary healthcare · 2025Article
- Is a day 7 blastocyst predictive of the reproductive potential of sibling day 5 and day 6 blastocysts?Journal of assisted reproduction and genetics · 2024Article
- Comparative Assessment of Survival and Clinical Outcome Between Two Commercial Vitrification Kits with Different Warming Protocols After Blastocyst Culture: Potential Perspectives Toward Simplified Warming Procedures.Reproductive sciences (Thousand Oaks, Calif.) · 2023Article
- Pregnancy Outcomes for Day 5 Versus Day 6 Single Frozen-thawed Blastocyst Transfer with Different Qualities of Embryos: A Large Matched-cohort Study.Current medical science · 2023Article
- The pregnancy outcomes of day-5 poor-quality and day-6 high-quality blastocysts in single blastocyst transfer cycles.Clinical and experimental reproductive medicine · 2023Article
- Comparison of clinical outcomes for different morphological scores of D5 and D6 blastocysts in the frozen-thawed cycle.BMC pregnancy and childbirth · 2023Article
- Comparative Embryo Development Outcomes following Extending Embryo Culture to Day 6: A Retrospective Cohort Study.International journal of fertility & sterility · 2023Article
- D6 high-quality expanded blastocysts and D5 expanded blastocysts have similar pregnancy and perinatal outcomes following single frozen blastocyst transfer.Frontiers in endocrinology · 2023Article
- Post-Thaw Day 5 Blastocyst Culture Time Prior to Transfer Does Not Affect Assisted Reproduction Technology (ART) Outcomes in Frozen-Thawed Embryo Transfer Cycles.Journal of clinical medicine · 2022Article
- Day of trophectoderm biopsy and embryo quality are associated with outcomes following euploid embryo transfer.Journal of assisted reproduction and genetics · 2022Article
- Great Challenges Remain for niPGT-A Reliability.Revista brasileira de ginecologia e obstetricia : revista da Federacao Brasileira das Sociedades de Ginecologia e Obstetricia · 2022Article
- Live birth rate following frozen-thawed blastocyst transfer is higher in high-grade day 6 blastocysts than in low-grade day 5 blastocysts.Frontiers in endocrinology · 2022Article
- First Baby Born in Brazil after Simultaneous Diagnosis through Non-Invasive and Conventional PGT-A.Revista brasileira de ginecologia e obstetricia : revista da Federacao Brasileira das Sociedades de Ginecologia e Obstetricia · 2021Article
- Embryo quality, ploidy, and transfer outcomes in male versus female blastocysts.Journal of assisted reproduction and genetics · 2021Article
- Day 5 vitrified blastocyst transfer versus day 6 vitrified blastocyst transfer in oocyte donation program.Scientific reports · 2021Article
Corrections and comments
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Authors and funding
6 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
purposeAn investigation into the clinical implications of delayed blastulation (day 5 versus day 6) was carried out for cryo cycles, as heterogeneous results persist in the current literature.
methodsWe performed a retrospective study comparing clinical pregnancies and live births between 178 blastocysts vitrified and warmed on day 5 versus 149 on day 6. The stage of blastocyst development was taken into account and adjustment for confounding factors was performed.
resultsOur results demonstrate a significant difference in clinical pregnancy (43 versus 23% p value < 0.001) and live birth rates (34 versus 16% p value < 0.001) regarding the day of vitrification, in favour of day 5. This difference persisted after adjustment for confounding factors. The adjusted odds ratio for clinical pregnancies and deliveries for the day 5 group compared to that of the day 6 group was 2.83 (95%CI, 1.48 to 5.41) and 2.94 (95%CI, 1.39 to 6.22), respectively. When the stage of development of the blastocyst was taken into consideration, we still observed a significant advantage of day 5 versus day 6 vitrification.
conclusionsDay of vitrification (day 5 versus day 6) appears to be an independent predictor of clinical outcomes. Stratification of our cohort was carried out according to the developmental stage, and significant differences persisted. Although the transfer of day 6 cryopreserved embryos remains a viable option, giving priority to a day 5 embryo would reduce the time to pregnancy.
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