Cumulative live birth rate of a blastocyst versus cleavage stage embryo transfer policy during in vitro fertilisation in women with a good prognosis: multicentre randomised controlled trial.
Cornelisse S, Fleischer K, van der Westerlaken L, de Bruin JP, Vergouw C, Koks C, Derhaag J, Visser J, van Echten-Arends J, Slappendel E, Arends B, van der Zanden M, van Dongen A, Brink-van der Vlugt J, de Hundt M, Curfs M, Verhoeve H, Traas-Hofmans M, Wurth Y, Manger P, Pieterse Q, Braat D, van Wely M, Ramos L, Mastenbroek S
- DOI
- 10.1136/bmj-2024-080133
- Record issued
- 2026-08-16
- Engine
- 7.39.0
- Exported
- 2026-09-22
Prepared by Alpha1. This document is confidential: it is intended for the recipient it was shared with and must not be redistributed. The live record at alpha1science.com/verify/02a08587-bbf4-414d-bc17-e3bacbce5237 is authoritative.
How this rating was calculated
- StatisticsImpossible or misreported statistic ×6−6★
- IntegrityIntegrity concern ×3−1.5★
- StatisticsPrinted percentage does not match its own count (capped) ×16−0.25★
- ReportingData & code availability partially met−0.25★
A demonstrable critical failure caps the rating at the minimum, regardless of the deductions above.
- The numeric-impossibility checks (GRIM/GRIMMER/DEBIT/SPRITE) did not run: 34 reported means were read, and their group size is not stated where the values are printed (this source has no machine-readable table structure). These checks need the count the mean was averaged over, so none was performed.
- No data or code availability links were detected to verify.
- 01Printed percentage does not match its own countdemonstrable
68.2% does not match the reported count 407/603
“GnRH agonist | 407 (68.2)”
Table 1Find in source - 02Printed percentage does not match its own countdemonstrable
9.2% does not match the reported count 31/350
“Small for gestational age (<10 centile)* | 31 (9.2)”
Table 4Find in source - 03Printed percentage does not match its own countdemonstrable
8.8% does not match the reported count 30/350
“Large for gestational age (>90 centile)* | 30 (8.8)”
Table 4Find in source - 04Printed percentage does not match its own countdemonstrable
6.2% does not match the reported count 21/350
“Low birth weight (<2500 g)* | 21 (6.2)”
Table 4Find in source - 05Printed percentage does not match its own countdemonstrable
4.7% does not match the reported count 16/350
“32-<37 weeks | 16 (4.7)”
Table 4Find in source - 06Printed percentage does not match its own countdemonstrable
24% does not match the reported count 81/350
“Caesarean delivery* | 81 (24.0)”
Table 4Find in source
16 further findings of this severity or below — every one is in the sections below, filed under its error type.
This Kaimen Rigor review uses Kaimen Rigor reviewers trained on a curated corpus of high-fidelity and retracted papers, with expert supervision and curation. It can still make mistakes; verify each finding against the source before relying on it.
This is a well-conducted and well-reported multicentre RCT comparing blastocyst versus cleavage stage embryo transfer policies. The study design is rigorous with appropriate randomization, blinding of analysts, and power analysis. The main weakness is the vague data availability statement, and there are minor copyediting issues including a potential sign inconsistency in Table 3.
Both reviewers classified the study as interventional, and this was adopted. The evaluation covered the full text, with all eight dimensions scored. The statistics verification component could only recompute a subset of tests (5 of 27) due to limited reporting; the remaining tests were not machine-verifiable and are not confirmed. The citation check found no retracted or unresolved references.
Numerical inconsistencies
3 findings · worst criticalValues that contradict each other or are impossible for the stated sample: recomputed p-values and test statistics, GRIM/GRIMMER checks on summary numbers, percentages against their own counts, totals against their parts, and estimates against their own confidence intervals.
- Summary statistic impossible for the stated N (GRIM/GRIMMER)Recomputed
- Printed percentage does not match its own countRecomputed
- Internal contradictions in the reported numbersAssessed
Recomputed 5 tests: 5 consistent, 0 inconsistent; 1 recomputed directly from the reported test statistics, 4 via agent-written checks. 6 reported summary statistics mathematically impossible for the stated N (PERCENT). 16 printed percentages that do not match their own count.
- PERCENT7.4% does not match the reported count 44/603
“Smoker | 44 (7.4)”
Table 1Find in source - PERCENT51.2% does not match the reported count 308/603
“Primary subfertility | 308 (51.2)”
Table 1Find in source - PERCENT31.8% does not match the reported count 190/603
“GnRH antagonist | 190 (31.8)”
Table 1Find in source - PERCENT68.2% does not match the reported count 407/603
“GnRH agonist | 407 (68.2)”
Table 1Find in source - PERCENT70.7% does not match the reported count 422/599
“GnRH agonist | 422 (70.7)”
Table 1Find in source - PERCENT73.6% does not match the reported count 441/603
“1 | 441 (73.6)”
Table 1Find in source - PERCENT72.4% does not match the reported count 432/599
“1 | 432 (72.4)”
Table 1Find in source - PERCENT18.7% does not match the reported count 112/603
“2 | 112 (18.7)”
Table 1Find in source - PERCENT19.8% does not match the reported count 118/599
“2 | 118 (19.8)”
Table 1Find in source - PERCENT8.8% does not match the reported count 52/599
“Fresh DET | 52 (8.8)”
Table 1Find in source - PERCENT0.6% does not match the reported count 1/603
“Technical problems | 1 (0.6)”
Table 1Find in source - PERCENT62.9% does not match the reported count 378/603
“Clinical pregnancy** | 378/603 (62.9)”
Table 2Find in source - PERCENT8% does not match the reported count 28/355
“Small for gestational age (<10 centile)* | 28 (8.0)”
Table 4Find in source - PERCENT9.2% does not match the reported count 31/350
“Small for gestational age (<10 centile)* | 31 (9.2)”
Table 4Find in source - PERCENT8% does not match the reported count 28/355
“Large for gestational age (>90 centile)* | 28 (8.0)”
Table 4Find in source - PERCENT8.8% does not match the reported count 30/350
“Large for gestational age (>90 centile)* | 30 (8.8)”
Table 4Find in source - PERCENT7.5% does not match the reported count 26/355
“Low birth weight (<2500 g)* | 26 (7.5)”
Table 4Find in source - PERCENT6.2% does not match the reported count 21/350
“Low birth weight (<2500 g)* | 21 (6.2)”
Table 4Find in source - PERCENT8.9% does not match the reported count 31/355
“32-<37 weeks | 31 (8.9)”
Table 4Find in source - PERCENT4.7% does not match the reported count 16/350
“32-<37 weeks | 16 (4.7)”
Table 4Find in source - PERCENT24.1% does not match the reported count 84/355
“Caesarean delivery* | 84 (24.1)”
Table 4Find in source - PERCENT24% does not match the reported count 81/350
“Caesarean delivery* | 81 (24.0)”
Table 4Find in source
- CONSISTENTreported p = .350 · recomputed p = .432Recomputed hazard ratio 1.06 (95% CI 0.92–1.23), reported p=0.35
“hazard ratio 1.06, 95% CI 0.92 to 1.23; P=0.35”
Taken as given: 0.92–1.23 is a two-sided 95% confidence interval for the hazard ratio of 1.06, not a range, an IQR, or a different interval level; the hazard ratio is a RATIO measure, so the interval is symmetric on the log scale; p=0.35 is the p for THIS estimate, not for another comparison in the same sentenceMethod: back the two-tailed p out of the log-scale CI width and compare it against the printed pHow we recomputed it: pCI(1.06, 0.92, 1.23, 1) - CONSISTENTreported p > .920 · recomputed p = .917Reviewers 1, 2Primary outcome risk ratio p-value from CI
“risk ratio 1.01, 95% CI 0.84 to 1.22”
Taken as given: The risk ratio is 1.01 with 95% CI 0.84 to 1.22.; The CI is two-sided at 95%.; The log of the risk ratio is approximately normally distributed.Method: Two-tailed p-value derived from the reported risk ratio and its 95% CI using the normal approximation.How we recomputed it: pCI(1.01, 0.84, 1.22, 1) - CONSISTENTreported p > .050 · recomputed p = .048Reviewers 1, 2Fresh transfer live birth risk ratio p-value from CI
“1.26, 1.00 to 1.58”
Taken as given: The risk ratio is 1.26 with 95% CI 1.00 to 1.58.; The CI is two-sided at 95%.; The log of the risk ratio is approximately normally distributed.Method: Two-tailed p-value derived from the reported risk ratio and its 95% CI using the normal approximation.How we recomputed it: pCI(1.26, 1.00, 1.58, 1) - CONSISTENTreported p < .030 · recomputed p = .034Reviewers 1, 2Moderate preterm birth risk ratio p-value from CI
“risk ratio 1.87, 95% CI 1.05 to 3.34”
Taken as given: The risk ratio is 1.87 with 95% CI 1.05 to 3.34.; The CI is two-sided at 95%.; The log of the risk ratio is approximately normally distributed.Method: Two-tailed p-value derived from the reported risk ratio and its 95% CI using the normal approximation.How we recomputed it: pCI(1.87, 1.05, 3.34, 1) - CONSISTENTreported p = .006 · recomputed p = .007Reviewer 2Pregnancy loss risk ratio p-value from CI
“0.68, 0.51 to 0.89”
Taken as given: The risk ratio is 0.68 and the 95% CI is 0.51 to 0.89.; The CI is two-sided at 95%.Method: Two-tailed p-value derived from the log risk ratio and its 95% CI using a normal approximation.How we recomputed it: pCI(0.68, 0.51, 0.89, 1)
- lowinternal contradictionIn Table 3, the mean difference for 'Women with no live birth' in embryo transfer procedures is reported as 0.54 with 95% CI −0.84 to −0.24, which is inconsistent because the point estimate is positive while the CI is entirely negative.
“Women with no live birth | 2.60 (1.60) | 3.15 (1.81) | 0.54 (−0.84 to −0.24) | <0.001”
Table 3Find in source - lowinternal contradictionThe abstract reports an absolute difference of 0.4 percentage points with CI -5.1 to 5.9, but the text in Results says '−5.1 to−5.9' which appears to be a typo (missing space).
“corresponding to an absolute difference of 0.4 percentage points (95% CI −5.1 to−5.9)”
ResultsFind in source - lowinternal contradictionIn Table 2, the pregnancy loss risk ratio for age >=36 is reported as '0.51 (0.35 to 0.74' with a missing closing parenthesis.
“0.51 (0.35 to 0.74”
Table 2Find in source
Overstated conclusions
None foundConclusions that reach past what the paper's own results support — including a significance claim that no longer holds when the statistic is recomputed, and efficacy resting on an unvalidated surrogate endpoint.
Checked — nothing surfaced.
7 major claims checked against the paper's own evidence: all adequately supported.
- supportedReviewers 1, 2Blastocyst stage embryo transfers resulted in a similar cumulative live birth rate to cleavage stage embryo transfers.The primary outcome shows no significant difference with a risk ratio of 1.01 and 95% CI crossing 1.Evidence: Primary outcome: 58.9% vs 58.4%, risk ratio 1.01 (95% CI 0.84 to 1.22).
“Blastocyst stage embryo transfers resulted in a similar cumulative live birth rate to cleavage stage embryo transfers in women with at least four embryos available during IVF treatment.”
ConclusionFind in source - supportedReviewer 1Blastocyst transfer is associated with a higher live birth rate after fresh embryo transfer.The risk ratio of 1.26 with 95% CI 1.00 to 1.58 supports a higher rate, though the lower bound is exactly 1.00.Evidence: Fresh transfer live birth rate: 37.0% vs 29.5%, risk ratio 1.26 (95% CI 1.00 to 1.58).
The live birth rate after fresh embryo transfer was higher in the blastocyst group, with live births in 223 (37.0%) of 603 women compared with 177 (29.5%) of 599 in the cleavage group (1.26, 1.00 to 1.58).
Resultsreviewer’s wording - supportedReviewer 1Blastocyst transfer is associated with a lower cumulative pregnancy loss rate.The risk ratio of 0.68 with 95% CI 0.51 to 0.89 supports a lower rate.Evidence: Cumulative pregnancy loss: 16.3% vs 24.2%, risk ratio 0.68 (95% CI 0.51 to 0.89).
The cumulative pregnancy loss rate was lower in the blastocyst group compared with cleavage group (16.3% v 24.2%; risk ratio 0.68, 95% CI 0.51 to 0.89).
Resultsreviewer’s wording - supportedReviewer 1Blastocyst transfer is associated with a higher incidence of moderate preterm birth in singletons.The risk ratio of 1.87 with 95% CI 1.05 to 3.34 supports a higher incidence.Evidence: Moderate preterm birth: 8.9% vs 4.7%, risk ratio 1.87 (95% CI 1.05 to 3.34).
“The incidence of moderate preterm birth (32 to <37 weeks) in singletons was higher in the blastocyst group, with an incidence of 8.9% compared with 4.7% in the cleavage group (risk ratio 1.87, 95% CI 1.05 to 3.34).”
ResultsFind in source - supportedReviewers 1, 2Blastocyst transfer reduces the number of embryo transfers needed to achieve a live birth.The mean number of transfers was lower in the blastocyst group with a significant p-value.Evidence: Mean number of transfers: 1.55 vs 1.82, P<0.001.
The mean number of embryo transfers needed to result in a live birth was lower in the blastocyst group compared with cleavage group (1.55 (0.99) v 1.82 (1.24), P<0.001).
Resultsreviewer’s wording - supportedReviewer 2Blastocyst transfer reduces pregnancy loss.The cumulative pregnancy loss rate was significantly lower in the blastocyst group (RR 0.68, 95% CI 0.51 to 0.89).Evidence: Secondary outcome: pregnancy loss 16.3% vs 24.2%, RR 0.68 (95% CI 0.51 to 0.89).
The cumulative pregnancy loss rate was lower in the blastocyst group compared with cleavage group (16.3% v 24.2%; risk ratio 0.68, 95% CI 0.51 to 0.89).
Resultsreviewer’s wording - supportedReviewer 2Blastocyst transfer increases moderate preterm birth.The incidence of moderate preterm birth was higher in the blastocyst group (RR 1.87, 95% CI 1.05 to 3.34).Evidence: Secondary outcome: moderate preterm birth 8.9% vs 4.7%, RR 1.87 (95% CI 1.05 to 3.34).
“The incidence of moderate preterm birth (32 to <37 weeks) in singletons was higher in the blastocyst group, with an incidence of 8.9% compared with 4.7% in the cleavage group (risk ratio 1.87, 95% CI 1.05 to 3.34).”
ResultsFind in source
Efficacy claim is anchored to an adequate endpoint and a meaningful effect.
- N/ASurrogate endpointThe primary outcome is cumulative live birth rate, a hard clinical outcome, not a surrogate.
“The primary outcome was the cumulative live birth rate per oocyte retrieval, including results of all frozen-thawed embryo transfers within a year after randomisation.”
- ADEQUATEEffect sizeThe primary outcome shows no significant difference between groups (risk ratio 1.01, 95% CI 0.84 to 1.22), with an absolute difference of 0.4 percentage points. The effect size is anchored to clinical meaningfulness by discussing that clinically relevant differences are unlikely but small differences cannot be ruled out.
“With an absolute difference of 0.4 percentage points (95% CI −5.1 to 5.9) in our study, clinically relevant differences are unlikely but small differences cannot be ruled out.”
Data authenticity concerns
None foundAn adversarial read for patterns associated with data that may not be genuine: results that look too clean, implausibly large effects, duplicated data or images, and methods that do not match the results reported.
Checked — nothing surfaced.
Reporting gaps
1 finding · worst mediumRequired detail the manuscript never states — study design, biological variables, ethics approval and consent, key resources, statistical reporting, data and code availability, and overall transparency.
- Data/code availability incompleteAssessed
The introduction cites systematic reviews and prior RCTs, explains the theoretical advantages of blastocyst transfer, and notes the lack of high-quality evidence on cumulative live birth rates. The rationale for the trial follows logically from the identified evidence gap. The paper acknowledges limitations of prior research, such as insufficient high-quality evidence on cumulative outcomes.
“Similarly, systematic reviews have concluded that high quality evidence on cumulative pregnancy results is currently insufficient and that well designed randomised controlled trials are needed to assess clinical value.”
“Nevertheless, it remains uncertain which of the two embryo transfers is superior in terms of cumulative live birth rate, encompassing live births from both fresh and frozen-thawed embryo transfers.”
“Similarly, systematic reviews have concluded that high quality evidence on cumulative pregnancy results is currently insufficient and that well designed randomised controlled trials are needed to assess clinical value.”
“Nevertheless, it remains uncertain which of the two embryo transfers is superior in terms of cumulative live birth rate, encompassing live births from both fresh and frozen-thawed embryo transfers.”
Randomization used an online computerised system with permuted blocks and stratification by age. Blinding of participants and clinicians was not feasible due to the nature of the intervention, but data analysts were masked. A sample size calculation was performed with 80% power and alpha 0.05. Inclusion/exclusion criteria were pre-specified. The analysis was intention-to-treat with per-protocol secondary analyses. Outlier handling is addressed through the ITT principle and handling of lost to follow-up.
“Women who had provided consent were randomly assigned in a 1:1 ratio using Castor, an online computerised randomisation software, on day 2 after oocyte retrieval.”
“Data analysts were masked during data cleaning and preparation of syntaxes, and they were unmasked after the inclusion and treatment phases.”
“We determined that a sample size of 1200 women would provide 80% power at an α level of 0.05, accounting for an estimated dropout rate of 2%.”
“Women who had provided consent were randomly assigned in a 1:1 ratio using Castor, an online computerised randomisation software, on day 2 after oocyte retrieval.”
“Participants, doctors, embryologists, and laboratory technicians could not be masked owing to the nature of the intervention. Data analysts were masked during data cleaning and preparation of syntaxes, and they were unmasked after the inclusion and treatment phases.”
“We determined that a sample size of 1200 women would provide 80% power at an α level of 0.05, accounting for an estimated dropout rate of 2%.”
The paper reports age, BMI, smoking status, and fertility history in Table 1. Both sexes are not applicable as participants are women. Demographics are adequately reported for the study population.
“Mean (SD) age (years) | 33.9 (4.2) | 34.1 (4.2)”
“Smoker | 44 (7.4) | 45 (7.6)”
“Mean (SD) age (years) | 33.9 (4.2) | 34.1 (4.2)”
The trial protocol was approved by the Central Committee on Research Involving Human Subjects (CCMO) with a protocol number. Written informed consent was obtained from all women. Regulatory compliance is implied through the approval process.
“The trial protocol was approved by the Central Committee on Research involving Human Subjects (The Hague, Netherlands) on 16 June 2018 (CCMO NL 64060.000.18)”
“Written informed consent was obtained from all women before oocyte retrieval.”
“The trial protocol was approved by the Central Committee on Research involving Human Subjects (The Hague, Netherlands) on 16 June 2018 (CCMO NL 64060.000.18)”
“Written informed consent was obtained from all women before oocyte retrieval.”
The trial involves an intervention (embryo transfer timing) rather than a drug or device. The intervention is described in detail. Statistical software (IBM SPSS version 28) is identified. No antibodies, cell lines, or other bench reagents are used.
“Statistical analysis was performed with IBM SPSS statistics (version 28).”
“In the blastocyst group, fresh embryos were transferred on day 5 (not day 6) after oocyte retrieval, followed by cryopreservation of surplus embryos on day 5 or day 6 using the vitrification method.”
“Statistical analysis was performed with IBM SPSS statistics (version 28).”
“In the blastocyst group, fresh embryos were transferred on day 5 (not day 6) after oocyte retrieval, followed by cryopreservation of surplus embryos on day 5 or day 6 using the vitrification method.”
The paper names the statistical tests used (chi-square, t-test, log-link binomial GLM, Cox regression). Effect sizes with 95% CIs are reported for primary and secondary outcomes. Exact p-values are given for some comparisons (e.g., P<0.001). Data presentation includes per-group n and confidence intervals. Mathematical plausibility checks were not possible for all values, but no obvious errors were found.
“We used the χ 2 test to assess differences in non-continuous variables between the two study groups and the independent t test to assess differences in continuous variables”
“risk ratio 1.01, 95% CI 0.84 to 1.22”
“We used the χ 2 test to assess differences in non-continuous variables between the two study groups and the independent t test to assess differences in continuous variables, reported as means.”
“The intention-to-treat cumulative live birth rate did not differ between the study groups, with live births in 355 (58.9%) of 603 women in the blastocyst group and 350 (58.4%) of 599 in the cleavage group (risk ratio 1.01, 95% CI 0.84 to 1.22)”
The data availability statement says restricted access can be arranged on request to the corresponding author, with proposals assessed by the study group. This is a managed-access statement but lacks specific conditions or a timeframe, making it reported_but_inadequate. No code sharing is applicable.
“Restricted access to the study data can be arranged on request to the corresponding author. Written proposals will be assessed by the ToF study group.”
“Restricted access to the study data can be arranged on request to the corresponding author. Written proposals will be assessed by the ToF study group. A data sharing agreement including terms and conditions for authorship and publication will need to be signed before data are available.”
The trial is registered (NTR7034). Funding sources and competing interests are declared. Limitations are discussed in detail. Conclusions are proportional to the evidence, with appropriate caveats for secondary outcomes. Methods are detailed enough for replication.
“Trial registration International Clinical Trial Registry Platform NTR7034.”
“The trial received a grant from the Leading the Change programme from Stichting Zorgevaluatie Nederland (project No 80-87600-98-19501)”
“Trial registration International Clinical Trial Registry Platform NTR7034.”
“Our trial has some limitations. We only included women with a minimum of four embryos available on day 2 after oocyte retrieval, limiting generalisability to women with fewer than four embryos.”
Registered (1 ID: Netherlands Trial Register). No reporting guideline cited.
Broken references and links
None found · partly checkedReferences checked against Crossref, OpenAlex and Retraction Watch for retractions and resolvability, plus declared data and code links probed for whether they resolve to content matching the paper.
Nothing surfaced — but not everything feeding this category ran (missing: data/code link verification), so read this as a partial clean bill.
Checked 35 references by DOI: 32 verified — 3 no DOI (shown, not verified).
- NO DOI2019 assisted reproductive technology fertility clinic and national summary reportNo DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
- NO DOIPlaatsing van een enkel embryo per ivf: antwoord op elke hulpvraag? [Single embryo implantation per IVF cycle: the answer to every request for assisted reproduction?]No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
- NO DOILandelijk IVF cijfers 2015No DOI in the reference — shown for manual review; not independently verifiable (not a fabrication signal).
Copyediting
5 minorWording, consistency and formatting errors that need correcting before submission.
No major wording or formatting errors. 5 minor suggestions below.
5 copyedit issues flagged: mostly consistency, clarity.
- MINORconsistencyAbstract, Results“58.9% (355 of 603) v 58.4% (350 of 599; risk ratio 1.01, 95% confidence interval (CI) 0.84 to 1.22)”→ Add closing parenthesis after '599' to match the opening parenthesis.Missing closing parenthesis in the abstract.
- MINORconsistencyTable 2, Pregnancy loss row“0.51 (0.35 to 0.74”→ Add closing parenthesis: '0.51 (0.35 to 0.74)'.Missing closing parenthesis in the table.
- MINORconsistencyTable 3, Women with no live birth, Mean difference“0.54 (−0.84 to −0.24)”→ Check if the mean difference should be negative; the CI is negative but the point estimate is positive.Potential sign inconsistency in the mean difference for embryo transfer procedures in women with no live birth.
- MINORclarityResults, Primary outcome“corresponding to an absolute difference of 0.4 percentage points (95% CI −5.1 to−5.9)”→ Change 'to−5.9' to 'to −5.9' for clarity.Missing space after 'to'.
- MINORconsistencyTable 2, footnote“0.51 (0.35 to 0.74”→ Add closing parenthesis: '0.51 (0.35 to 0.74)'.Missing closing parenthesis in the table.
The published work is robust and generally well-reported, but an informed reader should weigh the vague data availability statement and the minor internal inconsistencies flagged in the copyedit (e.g., the sign inconsistency in Table 3). These issues do not undermine the main conclusions but warrant a correction or clarification from the authors.
- 1.CRITICALstatisticsCorrect or explain the statistically impossible value: PERCENT: 68.2% does not match the reported count 407/603Demonstrable critical failure — blocks the verdict from passing.
- 2.CRITICALstatisticsCorrect or explain the statistically impossible value: PERCENT: 9.2% does not match the reported count 31/350Demonstrable critical failure — blocks the verdict from passing.
- 3.CRITICALstatisticsCorrect or explain the statistically impossible value: PERCENT: 8.8% does not match the reported count 30/350Demonstrable critical failure — blocks the verdict from passing.
- 4.CRITICALstatisticsCorrect or explain the statistically impossible value: PERCENT: 6.2% does not match the reported count 21/350Demonstrable critical failure — blocks the verdict from passing.
- 5.CRITICALstatisticsCorrect or explain the statistically impossible value: PERCENT: 4.7% does not match the reported count 16/350Demonstrable critical failure — blocks the verdict from passing.
- 6.CRITICALstatisticsCorrect or explain the statistically impossible value: PERCENT: 24% does not match the reported count 81/350Demonstrable critical failure — blocks the verdict from passing.
- 7.HIGHrigorIn Table 3, correct the mean difference for 'Women with no live birth' in embryo transfer procedures: the point estimate is 0.54 but the 95% CI is −0.84 to −0.24, which is internally inconsistent. Verify the correct value and sign, and update the table and any related text.An internal contradiction between a point estimate and its confidence interval is a validity threat that readers and reviewers will notice.
- 8.HIGHdata codeIn the Data availability statement, specify a concrete access mechanism (e.g., a named data access committee, a platform like YODA/Vivli, or a defined response timeframe) and the conditions for data sharing.The current statement is vague and does not meet common data availability standards, which is a transparency gap for a data-driven trial.
- 9.MEDIUMreportingIn the Methods or a separate section, explicitly state adherence to the CONSORT reporting guideline and provide the completed checklist as a supplementary file.Explicitly reporting guideline adherence improves transparency and reproducibility, and one reviewer flagged this as missing.
- 10.MEDIUMstatisticsIn the Statistical analysis section, clarify the handling of missing data for the obstetric questionnaire outcomes (e.g., imputation or sensitivity analysis).The paper notes incomplete responses but does not describe how missing data were handled, which is a reproducibility gap.
- 11.MEDIUMstatisticsReport exact p-values for all secondary outcomes where feasible, rather than only confidence intervals, to facilitate meta-analysis.Exact p-values are more informative and allow readers to combine results in future meta-analyses.
- 12.MEDIUMreportingProvide a link to the full study protocol or statistical analysis plan as a supplementary file to support reproducibility.A protocol link enhances transparency and allows readers to verify pre-specified analyses.
- 13.MEDIUMcopyeditIn the Abstract, Results, add the missing closing parenthesis after '599' in the sentence '58.9% (355 of 603) v 58.4% (350 of 599; risk ratio 1.01, 95% CI 0.84 to 1.22)'.The missing parenthesis is a minor typo that should be corrected for clarity.
- 14.MEDIUMcopyeditIn Table 2, add the missing closing parenthesis to the pregnancy loss risk ratio '0.51 (0.35 to 0.74'.The missing parenthesis is a minor formatting error that should be fixed.
- 15.MEDIUMcopyeditIn the Results, Primary outcome, change 'to−5.9' to 'to −5.9' for clarity.The missing space is a minor typo that affects readability.
- 16.LOWreportingIn the Discussion, explicitly state that the trial was not powered for subgroup analyses, making the existing implication more prominent.This clarifies the interpretation of subgroup findings and avoids over-interpretation.
- 17.LOWdata codeConsider depositing de-identified aggregate data in a public repository (e.g., Zenodo) with a DOI, if ethically permissible, to enhance transparency.Public data deposition would strengthen the data availability and allow independent verification.
The star rating is the report’s one-glance summary. Every paper starts at 5★ and loses stars for the concrete problems the review finds — so a rating is never a vague average, it’s a running total you can read line by line under “How this rating was calculated.”
- Reporting — 8 dimensionseach dimension that fully fails−½★
- each dimension partially met−¼★
- Statistics · Integrity · Claimseach serious problem−1★
- each medium problem−½★
- Citationseach retracted or unverifiable reference−¼★
- Copyeditonly when the manuscript needs a full edit−½★
The rating never drops below 1★, and a demonstrable critical failure (an impossible statistic, a proven ethics violation) caps it at 1★ on its own — so the stars can never look healthy when the verdict is CRITICAL.
The rating draws on a panel of agents. Three independent Kaimen Rigor reviewers grade the eight dimensions below across several independent passes (the shown verdict is their majority vote — steadier than any single run), isolate the paper’s major claims and check its own evidence backs them, and flag integrity concerns. Alongside them, a citation agent resolves every reference against Crossref, OpenAlex, and Retraction Watch; a statistics agent recomputes reported tests; and rule-based checks verify that declared data/code links actually resolve. Full text is required — an abstract-only submission is not analyzed.
Graded against NIH, MDAR, ARRIVE 2.0, CONSORT, EQUATOR, and RRID guidelines. A dimension that doesn’t apply to the study type is skipped, never penalized.
This Kaimen Rigor review is model-assisted and is not a substitute for formal expert review. It complements human evaluation by surfacing potential methodological concerns — verify each finding against the source.