Kaimen Rigor reviewed

Rigor-Reviewed Manuscript

Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy.

Name: Kaimen Rigor review — Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy.
Item: Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy.
Rating: 39
Author: Alpha1

Dwarkanath P, Muhihi A, Sudfeld CR, Wylie BJ, Wang M, Perumal N, Thomas T, Kinyogoli SM, Bakari M, Fernandez R, Raj JM, Swai NO, Buggi N, Shobha R, Sando MM, Duggan CP, Masanja HM, Kurpad AV, Pembe AB, Fawzi WW

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Kaimen Rigor review — 1★ (Critical), 1 critical, 3 high issues for “Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy.”

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Alpha1 Editorial

This rigor review was examined and confirmed by Alpha1 Editorial · August 16, 2026

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Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy.

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DOI

10.1056/NEJMoa2307212

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Issued Aug 16, 2026Engine 7.39.0

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Kaimen Rigor reviewed

Rigor-Reviewed Manuscript

Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy.

Paper source

Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy.

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 16, 2026

Kaimen Rigor review

Kaimen Rigor reviewed

1 / 5

Critical — a demonstrable failure

Interventional Study

Critical

High-priority

How this rating was calculated▸

Started at 5★ — deductions

StatisticsImpossible or misreported statistic−1★
StatisticsPrinted percentage does not match its own count (capped)−0.25★
ReportingData & code availability partially met−0.25★

A demonstrable critical failure caps the rating at the minimum, regardless of the deductions above.

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

Biggest issues1 demonstrable

01Significance claim does not survive recomputationdemonstrable
criticalOverreachrecomputedFull detail
Noninferiority p-value for preeclampsia in India trial (RR 0.84, 95% CI 0.68-1.03) vs margin 1.54
“relative risk, 0.84; 95% confidence interval [CI], 0.68 to 1.03”
Find in source
02Printed percentage does not match its own count
mediumArithmeticrecomputedFull detail
0.04% does not match the reported count 1/4475
“1/4475 (<0.1)”
Table 3Find in source

Findings by category

101ArithmeticNumerical inconsistencies 102OverreachOverstated conclusions 03AuthenticityNone found 104DisclosureReporting gaps 05AvailabilityNone found 06Copyedit2 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.

The paper reports two well-designed randomized noninferiority trials with strong methodology, clear reporting, and appropriate ethical approvals. The main weaknesses are a vague data sharing statement and a potential statistical inconsistency in a key noninferiority p-value that warrants verification.

Both reviewers agreed on study type (interventional) and on most dimensions. The statistical analysis dimension was downgraded from pass to warn based on the deterministic statistics check, which found one inconsistent p-value. The data code availability warning is based on the vague data sharing statement.

Numerical inconsistencies

1 finding · worst medium

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.

Printed percentage does not match its own countRecomputed

Recomputed 2 tests: 1 consistent, 1 inconsistent (1 change significance at p<.05); 2 via agent-written checks. 1 printed percentage that does not match its own count.

Overstated conclusions

1 finding · worst critical

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.

Significance claim flips when recomputedRecomputed

3 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

1 finding · worst medium

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.

Data/code availability incompleteAssessed

Eight Dimensions7 pass · 1 warn

The introduction cites WHO recommendations and placebo-controlled trials showing high-dose calcium reduces preeclampsia and preterm birth, and notes implementation barriers. It acknowledges limitations of prior low-dose trials (small sample sizes) and states the hypothesis that low-dose may be as efficacious as high-dose. The rationale links the premise to the study objectives.

Sub-criteria

prior work citedADEQUATE

premise rationaleADEQUATE

limitations addressedADEQUATE

Per reviewer (2) — the votes behind the verdict

PASSReviewer 1· 95% conf

The paper establishes a clear scientific premise based on WHO recommendations and prior trials, with a logical rationale for the hypothesis.

Evidence

“Calcium supplementation in pregnancy has been recommended by the World Health Organization (WHO) since 2011 to reduce the risk of preeclampsia in populations with low dietary calcium intake.”

Introduction ¶2Find in source

“Trials of low-dose calcium supplementation of less than 1000 mg per day in pregnancy, most of which evaluated a single 500-mg calcium supplement per day as compared with placebo and have had relatively small sample sizes, have generally shown a magnitude of reduction in the risks of preeclampsia and preterm birth similar to that seen in the trials of high-dose supplementation.”

Introduction ¶3Find in source

“We hypothesized that low-dose calcium supplementation in pregnancy may be as efficacious as high-dose supplementation with respect to the incidence of preeclampsia and preterm birth.”

Introduction ¶3Find in source

PASSReviewer 2· 90% conf

The paper establishes a clear scientific premise based on WHO recommendations and prior trials, with a logical rationale for testing low-dose calcium.

Evidence

“Calcium supplementation in pregnancy has been recommended by the World Health Organization (WHO) since 2011 to reduce the risk of preeclampsia in populations with low dietary calcium intake.”

Introduction ¶1Find in source

“We hypothesized that low-dose calcium supplementation in pregnancy may be as efficacious as high-dose supplementation with respect to the incidence of preeclampsia and preterm birth.”

Introduction ¶4Find in source

Introduction ¶3Find in source

Randomization used computer-generated block randomization stratified by clinic, with allocation concealment via prelabeled blister packs. Blinding was double-blind with identical tablets. Power analysis was performed for each trial with stated assumptions. Inclusion/exclusion criteria are clearly defined. The analysis population (ITT and per-protocol) is pre-specified, addressing outlier handling. Controls are inherent in the comparator arm. Independent replication is not applicable for a single pivotal trial.

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· 95% conf

The trials are well-designed with clear randomization, blinding, power analysis, and pre-specified inclusion/exclusion criteria.

Evidence

“The assignment sequence for each trial was generated by a statistician not otherwise involved in the trial by means of a computer-generated list of participant identification numbers with block randomization, stratified according to trial clinic.”

Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy.

Two Randomized Trials of Low-Dose Calcium Supplementation in Pregnancy.

Numerical inconsistencies

Overstated conclusions

Data authenticity concerns

Reporting gaps

Broken references and links

Copyediting

Numerical inconsistencies

Overstated conclusions

Data authenticity concerns

Reporting gaps

Broken references and links

Copyediting