SynthesisBMC pregnancy and childbirth2025
Embryonic and neonatal outcomes following double vitrification/thawing: a systematic review and meta-analysis.
Synthesis in BMC pregnancy and childbirth, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 1 paper.
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.
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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.
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Who cites it
1 citing paper in PubMed.
- Once, twice, three times frozen: viability and post-transfer outcomes of fresh and vitrified-warmed mouse embryos.Human reproduction (Oxford, England) · 2026Article
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Authors and funding
6 authors.
Funding
No grant is acknowledged in the PubMed record.
Abstract
objectivesThis systematic review and meta-analysis aimed to evaluate the impact of double vitrification/thawing (DVT) versus single vitrification/thawing (SVT) on key embryonic and neonatal outcomes. DATA EXTRACTION: Information sources included systematic search in PubMed, Scopus, and Cochrane databases up to September 7, 2024. Data from each qualifying study were extracted by two reviewers using a standardized electronic data gathering form. DATA ANALYSIS: Mantel-Haenszel odds ratio (MHOR) and mean difference (MD) with 95% confidence intervals (CI) were calculated using both fixed and random-effects models. Subgroup analyses were based on biopsy status, number of biopsy rounds, extended culture between rounds of vitrification, and embryo transfer strategy.
resultsA total of 35 studies involving 46,749 embryo transfer cycles were included. After excluding studies that used slow freezing, 28 studies were included in the meta-analyses. The findings indicated that DVT is associated with significant reductions in cryosurvival rates (MHOR: 0.4; CI: 0.3 to 0.8; P < 0.01), biochemical pregnancy (MHOR: 0.7; CI: 0.6 to 0.8; P < 0.01), clinical pregnancy (MHOR: 0.7; CI: 0.5 to 0.8; P < 0.01), and live birth rates (MHOR: 0.6; CI: 0.5 to 0.7; P < 0.01). Additionally, there was a significant increase in the miscarriage rate (MHOR: 1.4; CI: 1.2 to 1.7; P < 0.01). No significant differences were found in neonatal outcomes.
conclusionPoor-quality evidence suggests that the transfer of double-vitrified embryos might be associated with significantly lower rates of cryosurvival, pregnancy, and live births; however, it does not appear to affect neonatal outcomes such as birth weight and gestational age at birth. Given the small sample size in some subgroups, the high risk of selection, confounding and missing data biases, and the high level of heterogeneity for some outcomes, these findings should be interpreted cautiously.
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