Kaimen Rigor reviewed

Rigor-Reviewed Manuscript

Frozen versus fresh embryo transfer in women with low prognosis for in vitro fertilisation treatment: pragmatic, multicentre, randomised controlled trial.

Name: Kaimen Rigor review — Frozen versus fresh embryo transfer in women with low prognosis for in vitro fertilisation treatment: pragmatic, multicentre, randomised controlled trial.
Item: Frozen versus fresh embryo transfer in women with low prognosis for in vitro fertilisation treatment: pragmatic, multicentre, randomised controlled trial.
Rating: 100
Author: Alpha1

Wei D, Sun Y, Zhao H, Yan J, Zhou H, Gong F, Zhang A, Wang Z, Jin L, Bao H, Zhao S, Xiao Z, Qin Y, Geng L, Cui L, Sheng Y, Sun M, Liu P, Ding L, Liu H, Wu K, Li Y, Lu Y, Xu B, Xu B, Zhang L, Zhang H, Legro RS, Chen ZJ

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Kaimen Rigor review — 4★ (Strong), 0 critical, 2 high issues for “Frozen versus fresh embryo transfer in women with low prognosis for in vitro fertilisation treatment: pragmatic, multicentre, randomised controlled trial.”

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Alpha1 Editorial

This rigor review was examined and confirmed by Alpha1 Editorial · August 15, 2026

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Frozen versus fresh embryo transfer in women with low prognosis for in vitro fertilisation treatment: pragmatic, multicentre, randomised controlled trial.

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DOI

10.1136/bmj-2024-081474

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Kaimen Rigor reviewed

Rigor-Reviewed Manuscript

Frozen versus fresh embryo transfer in women with low prognosis for in vitro fertilisation treatment: pragmatic, multicentre, randomised controlled trial.

Paper source

Frozen versus fresh embryo transfer in women with low prognosis for in vitro fertilisation treatment: pragmatic, multicentre, randomised controlled trial.

Read full text (PMC)

Embed this Rigor badge

Links back to this Kaimen Rigor review.

Alpha1 Editorial

This rigor review was examined and confirmed by Alpha1 Editorial · August 15, 2026

Kaimen Rigor review

Kaimen Rigor reviewed

4 / 5

Strong — minor issues to address

Interventional Study

Critical

High-priority

How this rating was calculated▸

Started at 5★ — deductions

IntegrityIntegrity concern ×2−1★

Model-reported confidence: highReviewer agreement: highEngine: 7.39.0Source: full text

Findings by category

101ArithmeticNumerical inconsistencies 02OverreachNone found 03AuthenticityNone found 04DisclosureNone found 05AvailabilityNone found 06Copyedit5 minor suggestions

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 transparently reported pragmatic randomised controlled trial. The design is rigorous, with adequate randomization, sample size justification, and pre-specified analyses. Minor reporting gaps include lack of explicit CONSORT adherence and a slight inconsistency in live birth definition.

Both reviewers independently scored all dimensions as pass with high confidence, and their evidence was consistent. The study type is interventional (RCT). Non-applicable sub-criteria (e.g., animal housing, cell line authentication) were excluded. The statistics verification recomputed 3 tests, all consistent; however, this does not confirm the entire statistical analysis.

Numerical inconsistencies

1 finding · worst low

Values 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.

Internal contradictions in the reported numbersAssessed

Recomputed 3 tests: 3 consistent, 0 inconsistent; 3 via agent-written checks.

Overstated conclusions

None found

Conclusions 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.

4 major claims checked against the paper's own evidence: all adequately supported.

Efficacy claim is anchored to an adequate endpoint and a meaningful effect.

Data authenticity concerns

None found

An 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

None found

Required detail the manuscript never states — study design, biological variables, ethics approval and consent, key resources, statistical reporting, data and code availability, and overall transparency.

Checked — nothing surfaced.

Eight Dimensions8 pass

The introduction cites prior research on freeze-all strategies in normal/good prognosis women and notes the lack of evidence in low prognosis women. The hypothesis follows logically from the cited evidence and the authors' previous trials. Limitations of prior research (observational studies with inconsistent results) are acknowledged.

Sub-criteria

prior work citedADEQUATE

premise rationaleADEQUATE

limitations addressedADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The paper establishes a clear scientific premise with prior work cited and a logical rationale for the hypothesis.

Evidence

“Randomised trials found that compared with fresh embryo transfer, the freeze-all strategy yielded a comparable or higher rate of live birth in women with normal or good prognosis. Whether women with low prognosis benefit from the freeze-all strategy is, however, unclear.”

Introduction ¶3Find in source

“Based on our previous trials and the possible adverse effect of superovulation on the endometrium, we tested the hypothesis that frozen embryo transfer would result in a higher rate of live birth compared with fresh embryo transfer in women with a low prognosis.”

IntroductionFind in source

“Current evidence on the efficiency of the freeze-all strategy compared with fresh embryo transfer in women with a low prognosis is primarily from observational studies with inconsistent results.”

Introduction ¶3Find in source

PASSReviewer 2· 90% conf

The paper establishes a clear scientific premise with prior work cited, a logical rationale, and addresses limitations of prior research.

Evidence

Introduction ¶3Find in source

IntroductionFind in source

Randomization was centralized and stratified by age and site, with the sequence inaccessible to recruiters. Blinding was not feasible in this pragmatic trial, but the open-label design is inherent to the intervention and acknowledged. A priori sample size calculation is provided. Inclusion/exclusion criteria are clearly defined. The analysis populations (ITT, per-protocol, per-treatment) are pre-specified, addressing missing data and crossovers.

Sub-criteria

controlsN/A

power analysisADEQUATE

blinding levelsADEQUATE

outlier handlingADEQUATE

randomization unitADEQUATE

inclusion exclusionADEQUATE

randomization methodADEQUATE

replicate distinctionN/A

independent replicationN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The trial design is rigorous with adequate randomization, blinding considerations, power analysis, and pre-specified analysis populations.

Evidence

“The randomisation sequence was generated by the data-coordinating centre in Shandong University and input into the online central randomisation platform ( http://www.medresman.org ), which was inaccessible to the researchers responsible for recruitment and enrolment.”

MethodsFind in source

“With 80% power at a two-sided significance level of 0.05, we determined that the minimum total sample size was 713. Taking into account a 15% drop-out rate, we planned to enrol 838 women.”

MethodsFind in source

“In the secondary analyses, as prespecified in the study protocol, we performed per protocol analysis in women who complied with the study protocol, excluding those with protocol deviations, and per treatment analysis according to the actual treatment that women received.”

Statistical analysisFind in source

PASSReviewer 2· 90% conf

The trial design is rigorous with adequate randomization, blinding considerations, power analysis, and pre-specified analyses.

Evidence

MethodsFind in source

“With 80% power at a two-sided significance level of 0.05, we determined that the minimum total sample size was 713.”

MethodsFind in source

“After randomisation, both women and their doctors were informed about the assignment.”

MethodsFind in source

The trial reports age, BMI, duration of infertility, and ovarian reserve markers (AFC, AMH, FSH, LH, estradiol) in Table 1. Both sexes are not applicable as participants are women. Demographics are limited to age and BMI, but these are the relevant biological variables for this fertility trial.

Sub-criteria

demographicsADEQUATE

sex reportedADEQUATE

sex justifiedN/A

age weight healthADEQUATE

housing conditionsN/A

species strain sourceN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Key biological variables (age, BMI, infertility duration, ovarian reserve markers) are reported for both groups.

Evidence

paraphrase[Table 1]

“Age (years) | 34.0 (31.0-37.0) | 33.0 (31.0-37.0) | | BMI | 22.6 (20.3-24.8) | 22.6 (20.5-25.1)”

“AMH (pmol/L) | 10.9 (7.2-16.9) | 11.6 (7.3-17.8)”

Table 1Find in source

PASSReviewer 2· 90% conf

Relevant biological variables for a human trial are reported, including age, BMI, and infertility characteristics.

Evidence

“Age (years) | 34.0 (31.0-37.0) | 33.0 (31.0-37.0)”

Table 1Find in source

“Duration of infertility (years) | 3.0 (2.0-5.0) | 3.0 (1.5-5.0)”

Table 1Find in source

The paper states approval by the ethics committee of Hospital for Reproductive Medicine Affiliated to Shandong University (ID: 2020-38) and all participating centres. Written informed consent was obtained from all patients. Regulatory compliance is implied by adherence to standard trial conduct, though not explicitly named.

Sub-criteria

iacuc statementN/A

informed consentADEQUATE

irb ethics statementADEQUATE

regulatory complianceINADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

Ethical approval from a named committee and written informed consent are reported.

Evidence

“The trial was approved by the ethics committee of Hospital for Reproductive Medicine Affiliated to Shandong University (ID: 2020-38) and all participating centres.”

EthicsFind in source

“All patients provided written informed consent.”

EthicsFind in source

PASSReviewer 2· 95% conf

Ethical approval and informed consent are clearly documented.

Evidence

“The trial was approved by the ethics committee of Hospital for Reproductive Medicine Affiliated to Shandong University (ID: 2020-38) and all participating centres.”

EthicsFind in source

“All patients provided written informed consent.”

EthicsFind in source

The trial uses named medications with manufacturers (Crinone; Merck Serono, Duphaston; Abbott, Progynova; Delpharm Lille). Software used for analysis (SAS 9.4) and sample size (PASS 14.0) are identified. No antibodies, cell lines, or organisms are applicable.

Sub-criteria

mycoplasma testingN/A

reagents identifiedADEQUATE

organisms identifiedN/A

antibodies identifiedN/A

cell line authenticationN/A

software tools identifiedADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The investigational products (progesterone gel, dydrogesterone, estradiol valerate) are identified with brand names and manufacturers.

Evidence

“luteal phase support was initiated with vaginal progesterone gel (Crinone; Merck Serono) 90 mg daily and oral dydrogesterone (Duphaston; Abbott) 10 mg twice daily.”

MethodsFind in source

“SAS version 9.4 was used for all analyses.”

Statistical analysisFind in source

PASSReviewer 2· 90% conf

The investigational product (embryo transfer procedures) and key reagents are adequately identified.

Evidence

“luteal phase support was initiated with vaginal progesterone gel (Crinone; Merck Serono) 90 mg daily and oral dydrogesterone (Duphaston; Abbott) 10 mg twice daily.”

MethodsFind in source

“SAS version 9.4 was used for all analyses.”

Statistical analysisFind in source

Tests are named (χ², Fisher's, t-test, Wilcoxon rank sum). Normality was tested. Exact p-values are reported for primary and secondary outcomes. Effect sizes (relative ratios) with 95% CIs are provided. Software (SAS 9.4) is identified. Data presentation includes per-group n and percentages. Mathematical plausibility checks on reported percentages and counts are consistent.

Sub-criteria

tests namedADEQUATE

exact p valuesADEQUATE

effect sizes ciADEQUATE

data presentationADEQUATE

software identifiedADEQUATE

assumptions verifiedADEQUATE

mathematical plausibilityPASS

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Statistical methods are appropriate and well-described, with exact p-values and effect sizes with CIs.

Evidence

“the between group differences tested by χ 2 test or Fisher’s test with <5 expected frequency.”

Statistical analysisFind in source

paraphrase[Results, Primary outcome]

“132 (32%) of 419 women in the frozen embryo transfer group had a live birth compared with 168 (40%) of 419 in the fresh embryo transfer group (P=0.009), with a difference between groups of −8.6% (95% CI −15.1% to −2.1%) and a relative ratio of 0.79 (95% CI 0.65 to 0.94).”

PASSReviewer 2· 90% conf

Statistical methods are appropriate and well-described, with exact p-values and effect sizes with confidence intervals.

Evidence

“the between group differences tested by χ 2 test or Fisher’s test with <5 expected frequency.”

Statistical analysisFind in source

“132 (32%) of 419 women in the frozen embryo transfer group had a live birth compared with 168 (40%) of 419 in the fresh embryo transfer group (P=0.009)”

ResultsFind in source

“relative ratio of 0.79 (95% CI 0.65 to 0.94)”

ResultsFind in source

The data availability statement provides a direct link to a GitHub repository containing the data and code. This is a concrete access route, satisfying the requirement. The repository is public, so repository_deposit and accession_numbers are not applicable in the traditional sense but the GitHub link serves as the repository.

Sub-criteria

code sharingADEQUATE

accession numbersN/A

repository depositADEQUATE

data availability statementADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Data and code are openly available via a GitHub repository, and the data availability statement is concrete.

Evidence

“The data underlying the findings in this paper are openly and publicly available and can be found here: https://github.com/hepingzhangyale/FreFroLowProg.git”

Data availabilityFind in source

PASSReviewer 2· 90% conf

Data and code availability are adequately addressed with a public repository and code in supplemental files.

Evidence

“The data underlying the findings in this paper are openly and publicly available and can be found here: https://github.com/hepingzhangyale/FreFroLowProg.git”

Data availabilityFind in source

Trial registration number is provided (ChiCTR2100050168). Methods are comprehensive. Limitations are explicitly discussed, including the pragmatic design and embryo transfer differences. Conclusions are proportional to the evidence. Funding sources and competing interests are declared. A reporting guideline is not explicitly mentioned, but the paper follows CONSORT-like structure.

Sub-criteria

funding coiADEQUATE

trial registrationADEQUATE

reporting guidelineINADEQUATE

methods completenessADEQUATE

all outcomes reportedADEQUATE

limitations discussedADEQUATE

conclusions proportionalADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The trial is registered, methods are detailed, limitations are discussed, and funding/COI are declared.

Evidence

“Trial registration Chinese Clinical Trial Registry ChiCTR2100050168.”

AbstractFind in source

“Our study has some limitations. Firstly, as a pragmatic trial, we did not standardise the stimulation protocol, the number or stage of embryos for transfer, or the regimen for endometrial preparation in the frozen embryo group but followed clinical routines in study sites.”

LimitationsFind in source

PASSReviewer 2· 90% conf

The manuscript is transparent with complete methods, trial registration, and discussion of limitations.

Evidence

“Trial registration Chinese Clinical Trial Registry ChiCTR2100050168.”

AbstractFind in source

paraphrase[Discussion, Strengths and limitations]

“Our study has some limitations. Firstly, as a pragmatic trial, we did not standardise the stimulation protocol...”

paraphrase[Funding and Competing interests]

“Funding: The trial was funded by grants 31988101 from the Basic Science Center Program of National Natural Science Foundation of China...”

Registered (1 ID: Chinese Clinical Trial Registry). No reporting guideline cited.

Broken references and links

None found

References 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.

Checked — nothing surfaced.

Checked 41 references by DOI: 41 verified.

1 data/code link checked; 1 live.

Copyediting

5 minor

Wording, consistency and formatting errors that need correcting before submission.

No major wording or formatting errors. 5 minor suggestions below.

5 copyedit issues flagged: mostly typo, consistency, clarity.

Kaimen Rigor Action ItemsFinal pass before journal submission

The published work is robust and well-reported. An informed reader should weigh the minor inconsistencies (live birth definition, rounding of percentages) and the lack of explicit CONSORT adherence, but these do not undermine the main conclusions. No erratum is warranted for the identified issues, though clarifying the live birth definition would improve transparency.

1.
HIGHreporting
In the Methods or a dedicated section, explicitly state adherence to CONSORT reporting guidelines and provide the checklist as supplementary material.
Both reviewers noted that reporting guideline adherence is not explicitly stated, which is a common expectation for RCTs.
2.
HIGHreporting
Clarify the definition of live birth in the Methods to reconcile with the Table 4 footnote that includes two patients with live birth at 27 weeks.
The copyedit and integrity checks flagged an internal contradiction between the stated ≥28 weeks definition and the inclusion of 27-week births.
3.
MEDIUMcopyedit
Replace the term 'relative ratio' with 'risk ratio' or 'relative risk' consistently throughout the manuscript.
The copyedit flagged 'relative ratio' as non-standard terminology; consistency improves clarity.
4.
MEDIUMreporting
In the Ethics statements, explicitly state compliance with the Declaration of Helsinki or other regulatory framework.
Reviewer 1 noted that regulatory compliance is implied but not explicitly named; adding this strengthens the ethics reporting.
5.
MEDIUMdata code
Add a data dictionary or codebook to the GitHub repository to enhance usability of the public dataset.
Reviewer 2 suggested this to improve reproducibility and data usability.
6.
MEDIUMreporting
Add a statement about the availability of the full study protocol, if not already in supplementary materials.
Reviewer 2 suggested this to enhance transparency.
7.
LOWcopyedit
Rephrase the sentence in Methods, Statistical analysis about crossovers for clarity.
The copyedit flagged the sentence as slightly convoluted.
8.
LOWreporting
In the Discussion, explicitly address the lack of blinding as a limitation and its potential impact on outcomes.
Reviewer 1 suggested this to strengthen the limitations section.
9.
LOWstatistics
Clarify how missing data for laboratory tests (e.g., FSH, LH) were handled in the analysis.
Reviewer 1 suggested this to enhance statistical transparency.
10.
LOWreporting
In the Results, consider reporting the number of participants with missing data for each outcome.
Reviewer 1 suggested this to enhance transparency.
11.
LOWdata code
Provide the full statistical analysis code with comments in the supplementary material or repository.
Reviewer 1 suggested this to facilitate reproducibility.
12.
LOWreporting
In the Discussion, expand on the generalizability of the findings to other populations and settings.
Reviewer 1 suggested this to strengthen the discussion.

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Frozen versus fresh embryo transfer in women with low prognosis for in vitro fertilisation treatment: pragmatic, multicentre, randomised controlled trial.

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DOI

10.1136/bmj-2024-081474

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Issued Aug 15, 2026Engine 7.39.0

Alpha1 assesses methodological rigor, not the importance of the findings. See how we calibrate →

Kaimen Rigor review

Kaimen Rigor reviewed

4 / 5

Strong — minor issues to address

Interventional Study

Critical

High-priority

How this rating was calculated▸

Started at 5★ — deductions

IntegrityIntegrity concern ×2−1★

Model-reported confidence: highReviewer agreement: highEngine: 7.39.0Source: full text

Findings by category

101ArithmeticNumerical inconsistencies 02OverreachNone found 03AuthenticityNone found 04DisclosureNone found 05AvailabilityNone found 06Copyedit5 minor suggestions

Numerical inconsistencies

1 finding · worst low

Internal contradictions in the reported numbersAssessed

Recomputed 3 tests: 3 consistent, 0 inconsistent; 3 via agent-written checks.

Overstated conclusions

None found

Checked — nothing surfaced.

4 major claims checked against the paper's own evidence: all adequately supported.

Efficacy claim is anchored to an adequate endpoint and a meaningful effect.

Data authenticity concerns

None found

Checked — nothing surfaced.

Reporting gaps

None found

Checked — nothing surfaced.

Eight Dimensions8 pass

Sub-criteria

prior work citedADEQUATE

premise rationaleADEQUATE

limitations addressedADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The paper establishes a clear scientific premise with prior work cited and a logical rationale for the hypothesis.

Evidence

Introduction ¶3Find in source

IntroductionFind in source

Introduction ¶3Find in source

PASSReviewer 2· 90% conf

The paper establishes a clear scientific premise with prior work cited, a logical rationale, and addresses limitations of prior research.

Evidence

Introduction ¶3Find in source

IntroductionFind in source

Sub-criteria

controlsN/A

power analysisADEQUATE

blinding levelsADEQUATE

outlier handlingADEQUATE

randomization unitADEQUATE

inclusion exclusionADEQUATE

randomization methodADEQUATE

replicate distinctionN/A

independent replicationN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The trial design is rigorous with adequate randomization, blinding considerations, power analysis, and pre-specified analysis populations.

Evidence

MethodsFind in source

“With 80% power at a two-sided significance level of 0.05, we determined that the minimum total sample size was 713. Taking into account a 15% drop-out rate, we planned to enrol 838 women.”

MethodsFind in source

Statistical analysisFind in source

PASSReviewer 2· 90% conf

The trial design is rigorous with adequate randomization, blinding considerations, power analysis, and pre-specified analyses.

Evidence

MethodsFind in source

“With 80% power at a two-sided significance level of 0.05, we determined that the minimum total sample size was 713.”

MethodsFind in source

“After randomisation, both women and their doctors were informed about the assignment.”

MethodsFind in source

Sub-criteria

demographicsADEQUATE

sex reportedADEQUATE

sex justifiedN/A

age weight healthADEQUATE

housing conditionsN/A

species strain sourceN/A

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Key biological variables (age, BMI, infertility duration, ovarian reserve markers) are reported for both groups.

Evidence

paraphrase[Table 1]

“Age (years) | 34.0 (31.0-37.0) | 33.0 (31.0-37.0) | | BMI | 22.6 (20.3-24.8) | 22.6 (20.5-25.1)”

“AMH (pmol/L) | 10.9 (7.2-16.9) | 11.6 (7.3-17.8)”

Table 1Find in source

PASSReviewer 2· 90% conf

Relevant biological variables for a human trial are reported, including age, BMI, and infertility characteristics.

Evidence

“Age (years) | 34.0 (31.0-37.0) | 33.0 (31.0-37.0)”

Table 1Find in source

“Duration of infertility (years) | 3.0 (2.0-5.0) | 3.0 (1.5-5.0)”

Table 1Find in source

Sub-criteria

iacuc statementN/A

informed consentADEQUATE

irb ethics statementADEQUATE

regulatory complianceINADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

Ethical approval from a named committee and written informed consent are reported.

Evidence

“The trial was approved by the ethics committee of Hospital for Reproductive Medicine Affiliated to Shandong University (ID: 2020-38) and all participating centres.”

EthicsFind in source

“All patients provided written informed consent.”

EthicsFind in source

PASSReviewer 2· 95% conf

Ethical approval and informed consent are clearly documented.

Evidence

“The trial was approved by the ethics committee of Hospital for Reproductive Medicine Affiliated to Shandong University (ID: 2020-38) and all participating centres.”

EthicsFind in source

“All patients provided written informed consent.”

EthicsFind in source

Sub-criteria

mycoplasma testingN/A

reagents identifiedADEQUATE

organisms identifiedN/A

antibodies identifiedN/A

cell line authenticationN/A

software tools identifiedADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The investigational products (progesterone gel, dydrogesterone, estradiol valerate) are identified with brand names and manufacturers.

Evidence

“luteal phase support was initiated with vaginal progesterone gel (Crinone; Merck Serono) 90 mg daily and oral dydrogesterone (Duphaston; Abbott) 10 mg twice daily.”

MethodsFind in source

“SAS version 9.4 was used for all analyses.”

Statistical analysisFind in source

PASSReviewer 2· 90% conf

The investigational product (embryo transfer procedures) and key reagents are adequately identified.

Evidence

“luteal phase support was initiated with vaginal progesterone gel (Crinone; Merck Serono) 90 mg daily and oral dydrogesterone (Duphaston; Abbott) 10 mg twice daily.”

MethodsFind in source

“SAS version 9.4 was used for all analyses.”

Statistical analysisFind in source

Sub-criteria

tests namedADEQUATE

exact p valuesADEQUATE

effect sizes ciADEQUATE

data presentationADEQUATE

software identifiedADEQUATE

assumptions verifiedADEQUATE

mathematical plausibilityPASS

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Statistical methods are appropriate and well-described, with exact p-values and effect sizes with CIs.

Evidence

“the between group differences tested by χ 2 test or Fisher’s test with <5 expected frequency.”

Statistical analysisFind in source

paraphrase[Results, Primary outcome]

PASSReviewer 2· 90% conf

Statistical methods are appropriate and well-described, with exact p-values and effect sizes with confidence intervals.

Evidence

“the between group differences tested by χ 2 test or Fisher’s test with <5 expected frequency.”

Statistical analysisFind in source

“132 (32%) of 419 women in the frozen embryo transfer group had a live birth compared with 168 (40%) of 419 in the fresh embryo transfer group (P=0.009)”

ResultsFind in source

“relative ratio of 0.79 (95% CI 0.65 to 0.94)”

ResultsFind in source

Sub-criteria

code sharingADEQUATE

accession numbersN/A

repository depositADEQUATE

data availability statementADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

Data and code are openly available via a GitHub repository, and the data availability statement is concrete.

Evidence

“The data underlying the findings in this paper are openly and publicly available and can be found here: https://github.com/hepingzhangyale/FreFroLowProg.git”

Data availabilityFind in source

PASSReviewer 2· 90% conf

Data and code availability are adequately addressed with a public repository and code in supplemental files.

Evidence

“The data underlying the findings in this paper are openly and publicly available and can be found here: https://github.com/hepingzhangyale/FreFroLowProg.git”

Data availabilityFind in source

Sub-criteria

funding coiADEQUATE

trial registrationADEQUATE

reporting guidelineINADEQUATE

methods completenessADEQUATE

all outcomes reportedADEQUATE

limitations discussedADEQUATE

conclusions proportionalADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 90% conf

The trial is registered, methods are detailed, limitations are discussed, and funding/COI are declared.

Evidence

“Trial registration Chinese Clinical Trial Registry ChiCTR2100050168.”

AbstractFind in source

LimitationsFind in source

PASSReviewer 2· 90% conf

The manuscript is transparent with complete methods, trial registration, and discussion of limitations.

Evidence

“Trial registration Chinese Clinical Trial Registry ChiCTR2100050168.”

AbstractFind in source

paraphrase[Discussion, Strengths and limitations]

“Our study has some limitations. Firstly, as a pragmatic trial, we did not standardise the stimulation protocol...”

paraphrase[Funding and Competing interests]

“Funding: The trial was funded by grants 31988101 from the Basic Science Center Program of National Natural Science Foundation of China...”

Registered (1 ID: Chinese Clinical Trial Registry). No reporting guideline cited.

Broken references and links

None found

References 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.

Checked — nothing surfaced.

Checked 41 references by DOI: 41 verified.

1 data/code link checked; 1 live.

Copyediting

5 minor

Wording, consistency and formatting errors that need correcting before submission.

No major wording or formatting errors. 5 minor suggestions below.

5 copyedit issues flagged: mostly typo, consistency, clarity.

Kaimen Rigor Action ItemsFinal pass before journal submission

1.
HIGHreporting
In the Methods or a dedicated section, explicitly state adherence to CONSORT reporting guidelines and provide the checklist as supplementary material.
Both reviewers noted that reporting guideline adherence is not explicitly stated, which is a common expectation for RCTs.
2.
HIGHreporting
Clarify the definition of live birth in the Methods to reconcile with the Table 4 footnote that includes two patients with live birth at 27 weeks.
The copyedit and integrity checks flagged an internal contradiction between the stated ≥28 weeks definition and the inclusion of 27-week births.
3.
MEDIUMcopyedit
Replace the term 'relative ratio' with 'risk ratio' or 'relative risk' consistently throughout the manuscript.
The copyedit flagged 'relative ratio' as non-standard terminology; consistency improves clarity.
4.
MEDIUMreporting
In the Ethics statements, explicitly state compliance with the Declaration of Helsinki or other regulatory framework.
Reviewer 1 noted that regulatory compliance is implied but not explicitly named; adding this strengthens the ethics reporting.
5.
MEDIUMdata code
Add a data dictionary or codebook to the GitHub repository to enhance usability of the public dataset.
Reviewer 2 suggested this to improve reproducibility and data usability.
6.
MEDIUMreporting
Add a statement about the availability of the full study protocol, if not already in supplementary materials.
Reviewer 2 suggested this to enhance transparency.
7.
LOWcopyedit
Rephrase the sentence in Methods, Statistical analysis about crossovers for clarity.
The copyedit flagged the sentence as slightly convoluted.
8.
LOWreporting
In the Discussion, explicitly address the lack of blinding as a limitation and its potential impact on outcomes.
Reviewer 1 suggested this to strengthen the limitations section.
9.
LOWstatistics
Clarify how missing data for laboratory tests (e.g., FSH, LH) were handled in the analysis.
Reviewer 1 suggested this to enhance statistical transparency.
10.
LOWreporting
In the Results, consider reporting the number of participants with missing data for each outcome.
Reviewer 1 suggested this to enhance transparency.
11.
LOWdata code
Provide the full statistical analysis code with comments in the supplementary material or repository.
Reviewer 1 suggested this to facilitate reproducibility.
12.
LOWreporting
In the Discussion, expand on the generalizability of the findings to other populations and settings.
Reviewer 1 suggested this to strengthen the discussion.

Full text (52,024 chars)Analyzed: Aug 15, 2026