Effect of prolonged oocyte cryopreservation for >10 years on reproductive outcomes – a systematic review and meta-analysis
Bibliographic record
Abstract
Oocyte cryopreservation is essential for fertility preservation, yet the impact of prolonged cryostorage on cryosurvival, embryological and reproductive outcomes remains unclear. A systematic review and meta-analysis of 20 studies (2008-2023) from MEDLINE, Embase and Cochrane databases included 9901 patients. Nine large studies (mean cryostorage 3.76 years) were compared with 11 case studies (mean storage 10.2 years) to assess the impact of a longer period of cryostorage, as none of the large studies had ≥10 years of cryostorage. In large studies, cryosurvival was 81%, fertilization was 72%, and blastulation was 47%. Per embryo transferred (n = 9530), implantation, clinical pregnancy and live birth rates were 35%, 40% and 28%, respectively. Case studies showed comparable cryosurvival (76%), fertilization (76%) and blastulation (36%), with all reproductive outcomes exceeding 49%. A subanalysis of the case studies stratified by length of cryostorage comparing outcomes for ≥10 years (n = 6, mean 12.86 years) with <10 years (n = 5, mean 4.27 years) showed similar cryosurvival (74% versus 81%), lower fertilization (69% versus 91%; P = 0.028), comparable blastulation (37% versus 33%), and higher, although non-significant, clinical pregnancy and live birth rates (61% versus 33%). Available evidence, predominantly from case studies, suggests that prolonged cryostorage of oocytes does not compromise reproductive outcomes, although large prospective studies are needed.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.008 | 0.017 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.015 | 0.038 |
| Bibliometrics | 0.004 | 0.006 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.003 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.002 | 0.002 |
| Insufficient payload (model declined to judge) | 0.003 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".