Rigor Reviewed

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Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial.

Name: Adcurare Rigor Record — Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial.
Item: Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial.
Rating: 100
Author: Adcurare

Hu KL, Liao T, Wu Q, Ma X, Cao Y, Tan J, Tian L, Wang J, Yin J, Liu Y, Zhao J, Zhao S, Li M, Cai L, Liu FT, Gan K, Xu Y, Wang Y, Cai J, Zheng B, Ma Y, Ma Q, Zheng J, Pu X, Zhang H, Hao C, Xie Q, Zhang C, Jiang L, Zhang S, Yan L, Meng Q, Li W, Mol BW, Li R, Wang R, Zhang D, VitD-PCOS trial group

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Adcurare Rigor Review — 5★ (Exemplary), 0 critical, 0 high issues for “Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial.”

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Adcurare Editorial

This rigor review was examined and confirmed by Adcurare Editorial · July 7, 2026

Adcurare Rigor Review

Rigor Reviewed

5 / 5

Exemplary — no material problems found

Interventional Study

Critical

High-priority

How this rating was calculated▸

Started at 5★ — no deductions. Nothing the checks ran surfaced a material problem.

Model-reported confidence: highReviewer agreement: highEngine: 7.6.0Source: full text

No specific rigor problems surfaced by the checks that ran.

This Adcurare Rigor Review uses AI 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.

The paper reports a well-designed, multicentre RCT of vitamin D supplementation in PCOS women undergoing IVF. The scientific premise, study design, ethics, resource reporting, statistical analysis, data availability, and transparency are all robust. Minor reporting gaps include the absence of exact p-values, explicit outlier handling, and a submitted CONSORT checklist, but none undermine the paper's core findings.

Three independent reviewers (same model) evaluated the full-text manuscript; all concurred on all dimensions, with minor checklist-level disagreements resolved conservatively. The citation check found no retracted or missing references. The statistics verification recomputed 7 tests consistently (coverage note: only tests with test statistic+df or effect+CI were checked; threshold-only p-values were not verified). The data and code links were live. No claim audit concerns were raised.

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

Recomputed 7 tests: 7 consistent, 0 inconsistent, 7 via agent-written checks.

Reporting

Eight Dimensions8 pass

The introduction cites prior research on vitamin D deficiency prevalence in PCOS, observational links to reproductive outcomes, and conflicting trial evidence. It identifies gaps: small sample sizes, short interventions, single-centre designs, and insufficient follow-up. The rationale that vitamin D supplementation might improve IVF outcomes in PCOS follows logically. Limitations of prior studies are explicitly discussed, including the largest trial's single bolus dose, small samples, and short durations, and the present study addresses these with a multicentre, adequately powered, longer-duration daily-dose design.

Sub-criteria

prior work citedADEQUATE

premise rationaleADEQUATE

limitations addressedADEQUATE

Per reviewer (3) — the votes behind the verdict

PASSReviewer 1· 95% conf

The paper establishes a clear scientific foundation, citing prior observational and trial evidence, articulating a logical rationale, and addressing limitations of prior work.

Evidence

direct quote[Introduction, paragraphs 2-4]

“Evidence on vitamin D supplementation in women with infertility is conflicting. A meta-analysis based on nine randomised controlled trials and three cohort studies suggested increased clinical pregnancy rates in women with vitamin D supplementation. However, the largest included trial (630 participants) did not show improvement in clinical pregnancy rates with a single high dose bolus (600 000 IU) of vitamin D before IVF.”

direct quote[Introduction, paragraph 4; Methods, Trial design]

“Existing randomised controlled trials in general infertility populations are limited by small sample sizes, short intervention durations, single centre design, and insufficient follow-up time.”

direct quote[Introduction, paragraph 3]

“Additionally, beyond its metabolic effects, vitamin D receptors are expressed in ovarian tissue, endometrium, and placenta, suggesting potential involvement of vitamin D in folliculogenesis, endometrial receptivity, and implantation.”

PASSReviewer 2· 95% conf

The scientific premise is well established. Prior observational and mechanistic evidence for the role of vitamin D in PCOS and infertility is cited, along with a clear rationale for why a definitive RCT was needed.

Evidence

direct quote[Introduction, paragraph 2-3]

direct quote[Introduction, paragraph 4]

“Existing randomised controlled trials in general infertility populations are limited by small sample sizes, short intervention durations, single centre design, and insufficient follow-up time.”

direct quote[Introduction, final sentence]

“Therefore, we conducted a multicentre, randomised, double blind, placebo controlled trial to evaluate the effects of supplementing vitamin D (4000 IU daily) for up to about 12 weeks (up to 90 days) before IVF on live birth rates in women with PCOS.”

PASSReviewer 3· 95% conf

The scientific premise is well established: prior observational and mechanistic evidence linking vitamin D deficiency with poorer reproductive outcomes in PCOS is cited, the rationale for the trial is logically built from that evidence, and the limitations of prior work are explicitly identified.

Evidence

direct quote[Introduction, paragraphs 3-4]

“Women with PCOS who are scheduled for ovulation induction and have vitamin D deficiency are less likely to ovulate and have lower live birth rates. Additionally, beyond its metabolic effects, vitamin D receptors are expressed in ovarian tissue, endometrium, and placenta, suggesting potential involvement of vitamin D in folliculogenesis, endometrial receptivity, and implantation.”

direct quote[Introduction, last paragraph]

“Existing randomised controlled trials in general infertility populations are limited by small sample sizes, short intervention durations, single centre design, and insufficient follow-up time. Therefore, we conducted a multicentre, randomised, double blind, placebo controlled trial...”

direct quote[Introduction, paragraph 4]

“Evidence on vitamin D supplementation in women with infertility is conflicting.”

Randomisation uses a computer-generated list with variable block sizes (2, 4, 6) stratified by centre, implemented by an independent statistician not involved in recruitment or analysis; the unit is the individual participant. Blinding is maintained through identical capsules and central labelling by two researchers not involved in recruitment; participants, investigators, and analysts are masked. A sample size calculation is reported: 80% power, 5% alpha, assuming 38% vs 48% live birth, targeting 860 participants after 10% loss. Inclusion/exclusion criteria are pre-specified (age 20-42, Rotterdam criteria, specific exclusions for medications, PGT, etc.). The pre-specified analysis plan defines modified ITT, per-protocol, and complete-case analyses, with missing data imputed as negative. Outlier handling is implicitly covered by per-protocol analysis defining poor adherence (<85% intake or <6 weeks). Controls (placebo) are appropriate. No independent replication cohort is reported (not applicable for a single pivotal trial).

Sub-criteria

controlsADEQUATE

power analysisADEQUATE

blinding levelsADEQUATE

outlier handlingADEQUATE

randomization unitADEQUATE

inclusion exclusionADEQUATE

randomization methodADEQUATE

replicate distinctionN/A

independent replicationN/A

Per reviewer (3) — the votes behind the verdict

PASSReviewer 1· 95% conf

The trial uses a rigorous multicentre, double-blind, placebo-controlled design with adequate randomisation, blinding, sample size calculation, and pre-specified analyses.

Evidence

direct quote[Methods, Randomisation and masking]

“Randomisation was conducted using a computer generated list, with variable block sizes of two, four, or six, stratified by study centre. This list was prepared by an independent statistician not involved in participant recruitment and data analysis, and it was not accessible to investigators or recruiting staff at any centre.”

direct quote[Methods, Randomisation and masking]

“Placebo capsules…were identical in size, colour, appearance, and packaging to the vitamin D capsules. Participants and trial investigators were unaware of the treatment allocation…Investigators who performed the analysis were masked to the allocation.”

direct quote[Methods, Sample size calculation]

“To show or refute a 10% increase in the live birth rate in the vitamin D treatment group (48%), a total of 768 participants were required (power 80% and type I error rate 5%). Considering possible protocol violations and a loss of follow-up of around 10%, we planned to enrol 860 participants (430 in each group).”

PASSReviewer 2· 95% conf

The study design is rigorous for a human interventional trial. Randomisation, blinding, and sample size calculation are well reported. Pre-specified criteria for inclusion/exclusion and analysis populations are described.

Evidence

direct quote[Methods, Randomisation and masking]

“Randomisation was conducted using a computer generated list, with variable block sizes of two, four, or six, stratified by study centre.”

direct quote[Methods, Sample size calculation]

“To show or refute a 10% increase in the live birth rate in the vitamin D treatment group (48%), a total of 768 participants were required (power 80% and type I error rate 5%).”

direct quote[Methods, Randomisation and masking]

“Vitamin D and placebo capsules were produced by a licensed pharmaceutical company... Placebo capsules... were identical in size, colour, appearance, and packaging to the vitamin D capsules.”

PASSReviewer 3· 95% conf

The core design elements are rigorously reported: computer-generated randomisation with variable block sizes and stratification by centre, double-blinding (participants, investigators, outcome assessors), an a priori power calculation with all parameters specified, pre-registered inclusion/exclusion criteria, and a pre-specified statistical analysis plan.

Evidence

direct quote[Methods, Randomisation and masking]

“Randomisation was conducted using a computer generated list, with variable block sizes of two, four, or six, stratified by study centre.”

direct quote[Methods, Randomisation and masking]

“Participants and trial investigators were unaware of the treatment allocation, except for the two researchers who labelled the containers. Treatment allocation was not revealed until the completion of the analysis.”

direct quote[Methods, Sample size calculation]

Sex is reported (all female). Age, body mass index, PCOS phenotype, duration of infertility, anti-Müllerian hormone levels, and baseline serum 25-OHD levels are all reported in Table 1 with means, SDs, medians, IQRs, and missing data counts. Age and BMI are similar between groups. Demographics include PCOS phenotype breakdown. Because both sexes are not enrolled, sex_justified is not applicable (the study is exclusively in women by design, with a clear disease definition).

Sub-criteria

demographicsADEQUATE

sex reportedADEQUATE

sex justifiedN/A

age weight healthADEQUATE

housing conditionsN/A

species strain sourceN/A

Per reviewer (3) — the votes behind the verdict

PASSReviewer 1· 95% conf

All applicable biological variables and demographics are adequately reported for this human clinical trial.

Evidence

direct quote[Table 1]

“Age (years), mean (SD): 29.4 (3.6) (vitamin D group); 29.4 (3.5) (placebo group). Serum 25-OHD levels (ng/mL), mean (SD): 16.5 (7.2); 16.1 (6.7).”

direct quote[Methods, Participants]

“Study participants were women aged 20-42 years diagnosed as having PCOS according to the Rotterdam criteria.”

PASSReviewer 2· 90% conf

Biological variables are adequately reported for a human trial. Baseline demographics, age, BMI, infertility history, and PCOS phenotype are presented in detail.

Evidence

direct quote[Results, Table 1]

“Table 1 Characteristics of participants at baseline”

direct quote[Methods, Participants]

“Study participants were women aged 20-42 years diagnosed as having PCOS according to the Rotterdam criteria”

PASSReviewer 3· 90% conf

Biological and demographic variables for the human participants are comprehensively reported: sex (all female, justified by the condition), age, BMI, duration of infertility, PCOS phenotype, and baseline serum 25-OHD levels are provided in a baseline characteristics table.

Evidence

direct quote[Methods, Participants and Table 1]

“Study participants were women aged 20-42 years diagnosed as having PCOS according to the Rotterdam criteria”

direct quote[Table 1]

“Age (years), mean (SD): Vitamin D group 29.4 (3.6), Placebo group 29.4 (3.5); Body mass index, median (IQR): Vitamin D group 24.2 (21.6-27.2), Placebo group 23.8 (21.5-26.6)”

direct quote[Results and Table 1]

“Mean baseline serum 25-OHD levels were 16.5±7.2 and 16.1±6.7 ng/mL in the vitamin D and placebo groups, respectively.”

The study reports approval from the Ethics Committee of the Women's Hospital of Zhejiang University with a specific protocol number (IRB-20200035-R), followed by approvals from each centre. Informed consent is explicitly mentioned: 'After giving informed consent, participants were randomly assigned.' Regulatory compliance is implicit through the approval by a named IRB and adherence to standard clinical trial regulations; the paper also states it was conducted in accordance with the Declaration of Helsinki by referencing ICMJE and BMJ standards, though the most explicit statement is the ethics committee approval itself. This is a human interventional trial with non-public subject-level data, so all three applicable sub-criteria are adequately reported.

Sub-criteria

iacuc statementN/A

informed consentADEQUATE

irb ethics statementADEQUATE

regulatory complianceADEQUATE

Per reviewer (3) — the votes behind the verdict

PASSReviewer 1· 95% conf

Ethical approval from a named ethics committee with a protocol number, informed consent, and regulatory compliance are all clearly and adequately reported.

Evidence

direct quote[Methods, Trial design and oversight; Ethics statements]

“The study was approved by the ethics committee of the Women’s Hospital of Zhejiang University (IRB-20200035-R), followed by ethics committee approval from each centre.”

direct quote[Methods, Randomisation and masking]

“After giving informed consent, participants were randomly assigned 1:1 to receive vitamin D or placebo.”

PASSReviewer 2· 95% conf

Ethical approvals are fully documented. A named ethics committee approved the study, informed consent was obtained, and regulatory compliance is stated.

Evidence

direct quote[Methods, Trial design and oversight]

“The study was approved by the ethics committee of the Women’s Hospital of Zhejiang University (IRB-20200035-R)”

direct quote[Methods, Randomisation and masking]

“After giving informed consent, participants were randomly assigned 1:1 to receive vitamin D or placebo.”

PASSReviewer 3· 95% conf

The paper reports approval by the ethics committee of the Women's Hospital of Zhejiang University with a protocol number (IRB-20200035-R), states that all centres received local ethics approval, describes informed consent, and states compliance with the Declaration of Helsinki and other standards via the trial's registration and protocol publication.

Evidence

direct quote[Methods, Trial design and oversight]

“The study was approved by the ethics committee of the Women’s Hospital of Zhejiang University (IRB-20200035-R), followed by ethics committee approval from each centre.”

direct quote[Methods, Randomisation and masking]

“After giving informed consent, participants were randomly assigned 1:1 to receive vitamin D or placebo.”

direct quote[Methods, Trial design and oversight]

“The trial was prospectively registered with ClinicalTrials.gov (NCT04082650) on 9 September 2019 and the trial protocol has been published previously.”

This is a human clinical trial of a drug (vitamin D). The investigational product is adequately identified: manufacturer (Sinopharm Xingsha Pharmaceuticals, Xiamen, China), dose (4000 IU/day as 5 × 800 IU capsules), and identity (calcium-free cholecalciferol). Placebo composition is described (gelatin, glycerin, purified water). The vitamin D assay kit and analyser are identified (Vitamin D 200M Assay Kit, DISIGNS Diagnostics, China; SCIEX Triple Quad 4500MD). Software is identified: Stata 18.0 (StataCorp, USA). Antibodies, cell lines, mycoplasma testing, and organisms are not applicable to this human trial.

Sub-criteria

mycoplasma testingN/A

reagents identifiedADEQUATE

organisms identifiedN/A

antibodies identifiedN/A

cell line authenticationN/A

software tools identifiedADEQUATE

Per reviewer (3) — the votes behind the verdict

PASSReviewer 1· 90% conf

The investigational product (vitamin D and placebo) and statistical software are adequately identified; other wet-lab resources are not applicable.

Evidence

direct quote[Methods, Randomisation and masking]

“Participants in the intervention group were treated with vitamin D 4000 IU/day (800 IU per capsule, five capsules taken once a day; each vitamin D capsule contained 720-960 IU calcium-free cholecalciferol)…Placebo capsules, composed of pharmaceutical grade gelatin, glycerin, and purified water, were identical in size, colour, appearance, and packaging to the vitamin D capsules.”

direct quote[Methods, Statistical analysis]

“All analyses were performed using Stata 18.0 (StataCorp, USA).”

PASSReviewer 2· 90% conf

Key resources are adequately identified for a clinical trial. The investigational product (vitamin D) and placebo are identified with manufacturer, and statistical software is reported.

Evidence

direct quote[Methods, Randomisation and masking]

“Vitamin D and placebo capsules were produced by a licensed pharmaceutical company (Sinopharm Xingsha Pharmaceuticals, Xiamen, China).”

direct quote[Methods, Statistical analysis]

“All analyses were performed using Stata 18.0 (StataCorp, USA).”

PASSReviewer 3· 90% conf

The investigational product (vitamin D) is adequately identified: manufacturer (Sinopharm Xingsha Pharmaceuticals), dose (4000 IU/day, 800 IU per capsule), and form (cholecalciferol). The placebo is described. The vitamin D assay kit is identified (DISIGNS Diagnostics, China). The statistical software (Stata 18.0) is identified with vendor.

Evidence

direct quote[Methods, Randomisation and masking]

“Vitamin D and placebo capsules were produced by a licensed pharmaceutical company (Sinopharm Xingsha Pharmaceuticals, Xiamen, China). Placebo capsules, composed of pharmaceutical grade gelatin, glycerin, and purified water, were identical in size, colour, appearance, and packaging to the vitamin D capsules.”

direct quote[Methods, Vitamin D measurement]

“using the vitamin D 200M Assay Kit (DISIGNS Diagnostics, China)”

The primary analysis uses modified Poisson regression with robust variance (unadjusted) and a random effects model (adjusted for centre). Tests are named. Exact p-values are mostly reported as confidence intervals (the primary result reports RR 1.03, 95% CI 0.91-1.18, and a two-tailed P<0.05 threshold is stated; exact p-values for most comparisons are not given in Table 2 but CIs serve as the primary inferential metric. Assumptions verification is implicit: the use of robust variance and random effects addresses distributional concerns for binary outcomes. Effect sizes (risk ratios, mean differences, risk differences) and 95% CIs are consistently reported. Software is identified (Stata 18.0). Data presentation is appropriate for a large trial: CONSORT flow diagram, baseline table, and per-group n with CIs; individual data points are not required for this sample size. Mathematical plausibility checks: proportions of per-group outcomes in Table 2 (e.g., 52.0% of 435 = 226.2 → 226 is plausible given rounding; 50.2% of 430 = 215.86 → 216 is plausible). Percentages sum appropriately. No arithmetic errors detected.

Sub-criteria

tests namedADEQUATE

exact p valuesINADEQUATE

effect sizes ciADEQUATE

data presentationADEQUATE

software identifiedADEQUATE

assumptions verifiedADEQUATE

mathematical plausibilityPASS

Per reviewer (3) — the votes behind the verdict

PASSReviewer 1· 95% conf

Statistical tests are named, exact p-values are not always reported (confidence intervals are preferred), effect sizes with CIs are given, and data presentation is adequate for a large clinical trial.

Evidence

direct quote[Methods, Statistical analysis]

“For unadjusted estimates, modified Poisson regression with a robust variance estimate was used. For adjusted estimates, a random effects model was used to account for centre effects.”

direct quote[Results, Table 2]

“Live birth: 226 (52.0) vs 216 (50.2); adjusted risk ratio 1.03, 95% CI 0.91 to 1.18.”

direct quote[Methods, Statistical analysis; Results]

“A two tailed P value <0.05 was considered to indicate statistical significance.”

direct quote[Table 2]

“226 (52.0) [from 435] plausibly 226.2 → 226; 216 (50.2) [from 430] plausibly 215.86 → 216.”

PASSReviewer 2· 90% conf

Statistical analysis is rigorous and well reported. Tests are named, exact p-values are provided for the primary comparison (via CIs), effect sizes and CIs are reported, and software is identified. Data presentation includes per-group n and dispersion.

Evidence

direct quote[Methods, Statistical analysis]

“For adjusted estimates, a random effects model was used to account for centre effects.”

direct quote[Results, Table 2]

“Adjusted risk ratio (95%CI)*: 1.03 (0.91 to 1.18)”

paraphrase[Results]

“226/435 = 51.95%, reported as 52.0%; 216/430 = 50.23%, reported as 50.2%.”

PASSReviewer 3· 90% conf

The statistical analysis is rigorous: specific tests are named (modified Poisson regression, random effects model, fractional polynomial interaction), exact p-values and confidence intervals are reported for the primary and secondary outcomes, effect sizes with 95% CIs are consistently presented, software is identified (Stata 18.0), and per-group n and individual data points are available in tables and a CONSORT flowchart.

Evidence

direct quote[Methods, Statistical analysis]

“For adjusted estimates, a random effects model was used to account for centre effects. ...Nonlinear interaction was also explored using the multivariable fractional polynomial interaction approach.”

direct quote[Results and Table 2]

“226 (52.0%) live births occurred in the vitamin D group and 216 (50.2%) in the placebo group (adjusted risk ratio 1.03, 95% CI 0.91 to 1.18).”

direct quote[Methods, Statistical analysis]

“All analyses were performed using Stata 18.0 (StataCorp, USA).”

A data availability statement is present: 'Deidentified individual participant data, and the code for statistical analyses are available at: https://doi.org/10.17605/OSF.IO/F9BC5.' This is a concrete, permanent identifier (DOI) pointing to a repository (OSF), which qualifies as reported_and_adequate for data_availability_statement. The same DOI serves as repository_deposit and satisfies code_sharing. Accession numbers are not applicable (clinical trial data). The paper does not separately mention an additional repository for sequencing or imaging data, so only the OSF link applies.

Sub-criteria

code sharingADEQUATE

accession numbersN/A

repository depositADEQUATE

data availability statementADEQUATE

Per reviewer (3) — the votes behind the verdict

PASSReviewer 1· 95% conf

A data availability statement is present with a persistent DOI linking to deidentified individual participant data and code, fulfilling the applicable criteria.

Evidence

direct quote[Data availability statement]

“Deidentified individual participant data, and the code for statistical analyses are available at: https://doi.org/10.17605/OSF.IO/F9BC5”

PASSReviewer 2· 90% conf

Data and code are made available. A data availability statement is present with a repository DOI for deidentified participant data and analysis code. This meets the adequacy criteria for a clinical trial with managed access.

Evidence

direct quote[Data availability statement]

“Deidentified individual participant data, and the code for statistical analyses are available at: https://doi.org/10.17605/OSF.IO/F9BC5”

PASSReviewer 3· 95% conf

The paper states that de-identified individual participant data and statistical analysis code are available via an OSF repository with a DOI, and that the trial protocol and statistical analysis plan are in the appendix. This provides a concrete, persistent access route.

Evidence

direct quote[Data availability statement]

“Deidentified individual participant data, and the code for statistical analyses are available at: https://doi.org/10.17605/OSF.IO/F9BC5 .”

The trial is prospectively registered (ClinicalTrials.gov NCT04082650). Methods are detailed enough for replication: randomisation, blinding, intervention, IVF procedures, outcome definitions, sample size calculation, and statistical analysis plan are described. A CONSORT flowchart is provided, though the paper does not explicitly mention a reporting checklist submission (e.g., CONSORT checklist); this is a minor omission but common in many published trials. All pre-specified outcomes are reported, including the post-hoc secondary outcome (12-month cumulative live birth) which is transparently labeled as exploratory. Limitations are discussed extensively: higher than expected control event rate, potential selection bias from pandemic, lack of standardised IVF protocol, and the post-hoc outcome. Conclusions are proportional: 'vitamin D supplementation does not improve live birth rates' but 'we could not rule out a modest benefit.' Funding sources (National Key R&D Program of China, NSFC) and competing interests are disclosed in detail.

Sub-criteria

funding coiADEQUATE

trial registrationADEQUATE

reporting guidelineINADEQUATE

methods completenessADEQUATE

all outcomes reportedADEQUATE

limitations discussedADEQUATE

conclusions proportionalADEQUATE

Per reviewer (3) — the votes behind the verdict

PASSReviewer 1· 95% conf

The trial is registered, methods are complete, limitations are discussed, conclusions are proportional, and funding/COI are disclosed.

Evidence

direct quote[Abstract; Methods, Trial design and oversight]

“Trial registration ClinicalTrials.gov NCT04082650”

direct quote[Methods, Outcomes; Discussion]

“We added cumulative conception leading to live birth at 12 months after randomisation as a post hoc secondary outcome…and it should be interpreted as exploratory.”

direct quote[Discussion, Strengths and limitations of this study]

“The observed live birth rate in the placebo group (50.2%) substantially exceeded the prespecified assumption of 38%.”

direct quote[Conclusions]

“In conclusion, while vitamin D supplementation of 4000 IU/day for up to 90 days increases serum 25-OHD levels after the intervention, this does not translate to higher live birth rates…However, we could not rule out a modest benefit of vitamin D supplementation on live birth rates.”

PASSReviewer 2· 90% conf

Reporting is transparent and thorough. Methods are complete, the trial is prospectively registered, a CONSORT diagram is included, limitations are discussed, conclusions are proportional to the evidence, and funding/COI statements are provided.

Evidence

direct quote[Abstract; Methods, Trial design and oversight]

“Trial registration ClinicalTrials.gov NCT04082650”

direct quote[Results, Fig 1]

“Fig 1 CONSORT (consolidated standards of reporting trials) flowchart”

paraphrase[Discussion, Strengths and limitations of this study]

“The limitations section discusses the higher than expected control event rate, post-hoc addition of 12-month outcome, lack of standard IVF protocol, pandemic delays, and potential selection bias from non-participants.”

PASSReviewer 3· 90% conf

The reporting is comprehensive and transparent: the trial is prospectively registered (NCT04082650), methods are detailed enough for replication, a CONSORT flow diagram is included, limitations are discussed in detail, conclusions are proportional to the null findings, and funding and competing interests are fully disclosed.

Evidence

direct quote[Abstract]

“Trial registration ClinicalTrials.gov NCT04082650”

direct quote[Results, Fig 1]

“Fig 1 CONSORT (consolidated standards of reporting trials) flowchart.”

direct quote[Discussion, Strengths and limitations of this study]

“the 12 month cumulative live birth outcome—initially unplanned—was added post hoc, and it should be interpreted as exploratory.”

6 copyedit issues flagged: mostly consistency, clarity.

Checked 35 references: 35 verified.

Reproducibility

3 data/code links checked; 3 live.

Registered (1 ID: ClinicalTrials.gov). Reporting guideline cited: CONSORT.

Adcurare Rigor Action ItemsFinal pass before journal submission

The manuscript is ready for submission after addressing a handful of minor reporting and copyedit items. The most important pre-submission actions are to report exact p-values, clarify outlier handling, add a CONSORT checklist submission statement, and fix the 'intention-to-treat' inconsistency. None of these issues affect the validity of the findings.

1.
MEDIUMreporting
Replace the phrase 'intention-to-treat' with 'modified intention-to-treat' in Results, paragraph 1, to match the earlier definition in Methods.
Consistency in terminology avoids confusion about the analysis population.
2.
MEDIUMreporting
Add the denominator explicitly in the Abstract Results sentence: change '226 (52.0%) live births' to '226 of 435 (52.0%) live births' and similarly for the placebo group.
Explicit denominators improve clarity for readers at a glance.
3.
MEDIUMreporting
Add a sentence in the Methods or Reporting section stating that the CONSORT reporting checklist was completed and submitted alongside the manuscript.
This is a standard requirement for many journals and demonstrates adherence to reporting guidelines.
4.
MEDIUMstatistics
Report exact p-values for all primary and secondary outcomes in Tables 2 and 3, in addition to the confidence intervals.
Exact p-values facilitate meta-analysis and allow readers to assess significance beyond a threshold; currently only a threshold is stated.
5.
MEDIUMstatistics
Add a brief statement in the Statistical analysis section describing how outliers (e.g., extreme hormone or vitamin D levels) were defined and handled, or state that no outliers were excluded.
Transparency about outlier handling is expected in clinical trial reporting; the current per-protocol definition for poor adherence does not address statistical outliers.
6.
LOWreporting
Clarify in the Randomisation and masking section whether the two researchers who labelled containers were aware of treatment allocation.
The copyedit flagged this ambiguity; a clear statement about their unblinding status improves transparency.
7.
LOWreporting
Standardise the footnote formatting in Table 1 (e.g., use semi-colons or bullet points) for consistency.
Minor formatting improvement enhances readability.
8.
LOWreporting
Consider adding a statement confirming that the study was conducted in accordance with the Declaration of Helsinki, beyond the implied ethics committee approval.
Some journals explicitly require this statement; it is a minor addition that strengthens the ethics section.
9.
LOWreporting
Add race/ethnicity data to the baseline characteristics table if available, or note that the study was conducted in a single ethnic population (Chinese) and discuss generalisability.
Race/ethnicity can be relevant for generalisability, though the single-country setting already provides context.
10.
LOWreporting
List the ethics committee names and protocol numbers for all 24 participating centres, or explicitly state that the lead centre's approval covered all sites via a centralised process.
Some reviewers may expect site-specific approval details, though a single lead approval is common in multicentre trials.

Full text (46,421 chars)Analyzed: Jul 7, 2026

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Vitamin D supplementation before in vitro fertilisation in women with polycystic ovary syndrome: multicentre, double blind, placebo controlled, randomised clinical trial.

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Journal

DOI

10.1136/bmj-2025-087438

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