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Please accept my congratulations to the authors on this revised manuscript. I was impressed with their thoughtful and comprehensive response to the feedback. The paper is now clear, robust, and a valuable contribution to the field. I am very happy to endorse it.
**PeerJ Staff Note:** Although the Academic Editor is happy to accept your article as being scientifically sound, a final check of the manuscript shows that it would benefit from further English editing. Therefore, please identify necessary edits and address these while in proof stage.
The authors have addressed previous concerns thoroughly. Inconsistencies regarding education level and multiple-testing correction have been resolved, with consistent reporting in Results and Discussion. The Introduction and sEMG background are streamlined, language is clear, and all variables and thresholds are explicitly defined.
The retrospective design is appropriate for an exploratory study. Ultrasound and sEMG acquisition details, including electrode placement and rationale for omitting MVC normalization, are adequately described. Limitations due to single-center, short-duration recruitment are acknowledged.
Statistical reporting is comprehensive, including effect sizes, confidence intervals, and corrected p-values. The findings are appropriately framed as exploratory, given the absence of a priori power calculation.
Minor editorial polishing is suggested for formatting and English, but the scientific quality is unaffected. The manuscript is now clear, internally consistent, and suitable for publication.
Recommendation: Accept after minor editorial revisions.
I completely agree with one of the Reviewer 3's comments. Please address all the comments carefully.
Overall, the manuscript is written in generally clear English, but there are several sections where phrasing is ambiguous or contradictory. Notably, the reporting of education level is inconsistent: the Results section states that the DRA group had a “significantly higher level of education,” whereas the multivariable analysis and Discussion claim that “lower educational attainment” is a risk factor. This contradiction makes the interpretation unclear and undermines confidence in the results. Similar inconsistency is seen regarding the application of multiple-testing correction (Benjamini–Hochberg): the Methods section claims that it was applied, whereas the Limitations section states that no formal correction was used. Both issues must be resolved for the article to meet the criterion of clear, unambiguous reporting.
The introduction adequately describes the clinical relevance of diastasis recti abdominis (DRA) and provides citations to key prevalence studies (Sperstad et al., Beer et al., etc.). However, the rationale for choosing a 2-cm IRD cutoff should be better justified, as this decision substantially affects prevalence estimates. The background on sEMG and pelvic floor muscle function is appropriate, but could be condensed slightly and refocused on why surface EMG was selected and what gap it addresses.
The manuscript addresses its hypotheses (risk factors for DRA, relationship with PFM sEMG) and presents results that correspond to those aims. However, due to the lack of full data presentation and contradictory interpretation of key findings, the article cannot yet be considered fully self-contained.
Major Revision Required:
1. Resolve contradictions about education level and multiple-testing correction, and ensure consistent interpretation across Results and Discussion.
2. Provide full methodological detail for ultrasound and sEMG acquisition and processing, including signal normalization procedures or a justification if not used.
3. Include complete tables (baseline characteristics, regression results, sEMG parameters) with counts, means/SD or medians/IQR, effect sizes, p- and q-values.
4. Add a STROBE-compliant participant flow diagram and consider including representative ultrasound images and EMG traces.
5. Revise language for clarity and precision, ensuring all variables and thresholds are explicitly defined.
The research question—examining risk factors of diastasis recti abdominis (DRA) and its association with pelvic floor muscle (PFM) surface EMG characteristics in the early postpartum period—is appropriate and clinically meaningful. The retrospective design is acceptable for an exploratory observational study but does carry inherent limitations (e.g., potential selection bias, incomplete control of confounders). The inclusion and exclusion criteria are clearly described, which strengthens internal validity. However, several issues limit reproducibility and may introduce bias: Sample Representativeness: The study recruited participants from a single tertiary hospital in a 3-month window, which may limit generalizability. There is no discussion of whether these participants are representative of the broader postpartum population.
The data presented are generally consistent with the stated objectives, and the prevalence estimate of DRA at 6 weeks postpartum is within a plausible range based on prior literature. The use of ultrasound adds credibility to the accuracy of IRD measurement compared with palpation-based studies. The multivariate logistic regression model is appropriate in principle for identifying independent risk factors, and the presentation of odds ratios with confidence intervals is commendable.
However, several concerns affect the overall robustness of the findings: The authors do not provide a priori power calculation, leaving uncertainty as to whether the study was adequately powered to detect meaningful differences, particularly in subgroup comparisons and in the PFM sEMG analysis.
**PeerJ Staff Note:** Please ensure that all review, editorial, and staff comments are addressed in a response letter and that any edits or clarifications mentioned in the letter are also inserted into the revised manuscript where appropriate.
1. The manuscript's reporting has significantly improved.
The authors have addressed most of my concerns. It is highly appreciated.
2. For ultrasound measurements, the authors state only that measurements were taken by "a physiotherapist with specific training in image capturing and measuring IRD" (lines 80-81). However, critical details are missing regarding the nature, duration, and standardization of this training. The manuscript does not specify who provided the training, what competency assessments were conducted, or what protocols were used to ensure measurement standardization. Similarly, for sEMG measurements, the authors mention "another physiotherapist with more than three years of clinical experience in pelvic floor muscle sEMG" (lines 95-96). While experience duration is quantified, there is no information about specific training in the Glazer protocol, certification requirements, or standardization procedures for electrode placement and signal interpretation. Please provide this information.
3. The justification for not providing adjusted p-values is insufficient. See the "validity of findings."
4. The discussion requires further development. See "additional comments."
No comment
1. The authors successfully implemented multivariate logistic regression analysis and appropriately revised their terminology throughout the manuscript. Rather than claiming definitive "risk factors," they now correctly identify "factors associated with" DRA, which aligns with their analytical approach. The multivariate analysis reveals that older maternal age (OR=1.10, 95% CI: 1.04–1.16), lower educational attainment (OR=0.31, 95% CI: 0.18–0.55), and higher parity (OR=2.09, 95% CI: 1.30–3.37) are independently associated with increased risk of DRA. The revised tables now accurately include confidence intervals for key findings, and odds ratios with 95% confidence intervals are provided for the regression analysis, enhancing the clinical interpretability of the results.
2. The current justification for not providing adjusted p-values is insufficient. Please count the number of comparisons you performed and conduct a Benjamini-Hochberg correction for multiple comparisons. Report both corrected and uncorrected p-values. It would strengthen your paper and make your "exploratory findings" more credible for guiding future research. Your current approach risks reporting false positives as potential targets for future investigation.
1. Discuss which findings remain significant after Benjamini-Hochberg correction.
2. The discussion of the association between lower educational attainment and increased DRA risk (lines 198-207) requires substantial expansion to address this important finding adequately.
While the authors acknowledge that this relationship is "not widely documented," they provide only superficial speculation about potential mechanisms. The proposed pathway linking education to DRA through health literacy and exercise awareness lacks supporting evidence and represents only one of several possible explanations for this association.
-The discussion fails to provide adequate context by comparing this finding with existing literature on socioeconomic factors and pregnancy-related musculoskeletal conditions. Additionally, the authors do not explore alternative mechanisms that could explain this association, such as differences in healthcare access, nutritional status, occupational physical demands, or age at childbearing between educational groups.
-A critical limitation of the current discussion is the lack of acknowledgment that education often serves as a proxy for broader socioeconomic factors that were not measured in this study. The binary categorization of education may not capture the nuanced socioeconomic differences that could influence DRA development. The authors should discuss potential confounding variables and acknowledge the limitations of their education measurement.
-Furthermore, the clinical implications of this finding are not addressed. If educational attainment influences DRA risk, this has important implications for patient counseling, targeted prevention strategies, and resource allocation in postpartum care.
-The authors should provide a more comprehensive discussion that includes a comparison with relevant literature, exploration of multiple potential mechanisms, acknowledgment of confounding limitations, and consideration of clinical implications. Given the potential novelty and importance of this finding, it warrants more rigorous theoretical grounding and critical evaluation.
**PeerJ Staff Note:** Please ensure that all review and editorial comments are addressed in a response letter and that any edits or clarifications mentioned in the letter are also inserted into the revised manuscript where appropriate.
**Language Note:** The review process has identified that the English language must be improved. PeerJ can provide language editing services - please contact us at [email protected] for pricing (be sure to provide your manuscript number and title). Alternatively, you should make your own arrangements to improve the language quality and provide details in your response letter. – PeerJ Staff
Introduction:
The intro is well-written and introduces the reader to the subject.
The rationale for the study is clear.
The research question is well-defined, and the methodology is generally appropriate for the objectives. Using ultrasound imaging for DRA measurement and surface EMG for pelvic floor muscle activity assessment follow established protocols.
Measuring: It is unclear and unstated who or how many examiners performed the measurements. Also, reliability information is missing. Please add whether inter- and intra-reliability or both were performed and the protocol.
Also, what are the validity and reliability of your measuring protocols? Please add a description and references for the DRA distance measuring protocols and the rectus abdominis contraction.
Pelvic Floor EMG: This section also lacks a description of the measuring protocol; who or how many examiners performed the measuring? What is their experience? Were reliability studies conducted for the measuring? What were the calibration procedures for the equipment?
Other methodological concerns include:
1. Despite claiming to identify "risk factors," the authors did not perform multivariate regression analysis to control for confounding variables. Simple bivariate comparisons between groups cannot establish independent risk factors.
2. The authors report multiple statistical comparisons without apparent correction for multiple testing, which increases the risk of Type I errors.
3. While the authors mention using the Mann-Whitney U test for non-normally distributed data, they do not indicate which variables were non-normally distributed.
4. The sample size calculation and power analysis are not reported, making it difficult to assess whether the study was adequately powered to detect meaningful differences.
The primary findings regarding the association between certain factors (age, education level, parity, BMI, and fetal weight) and DRA are potentially valid. However, the claim that these are "risk factors" is not supported by the statistical analysis performed. A multivariate logistic regression would be necessary to identify independent risk factors.
The finding of no significant relationship between DRA and pelvic floor muscle EMG characteristics is more robust. However, the authors could better discuss the limitations of surface EMG measurements and potential confounding factors.
The raw data appears to have been appropriately analyzed for the statistical tests performed, but as mentioned, the analytical approach does not support the causal claims made in the conclusion.
1. Include inter, and intra-tester protocol and their outcomes in the results section.
2. The authors should revise their terminology from "risk factors" to "factors associated with" throughout the manuscript unless they perform appropriate multivariate regression analyses.
3. The high prevalence of DRA in this sample (72.6%) warrants more discussion. How does this compare to expected prevalence based on literature, and what might explain this finding?
4. The finding that education level is associated with DRA is unusual and requires further explanation and discussion. This finding, however, may be nonsignificant after regression.
5. The authors should report effect sizes, confidence intervals, and p-values to better indicate their findings' clinical significance.
6. The discussion should more critically evaluate the limitations of the retrospective design and surface EMG measurements.
Specific recommendations:
A. Perform multivariate logistic regression to correctly identify independent risk factors for DRA, adjusting for confounding variables.
B. Clarify how DRA was classified - while the authors state using >2cm as the cutoff, it's unclear whether this threshold was applied to any measurement point or required at all five measurement points.
C. Consider analyzing the relationship between the severity of DRA (not just its presence) and pelvic floor muscle function.
D. Address the unexpected finding regarding education level and its potential relationship with DRA should it remain significant after regression.
E. Provide more details on the reliability of the measurement techniques used.
In conclusion, while this study provides valuable observational data on factors associated with DRA in early postpartum women, the authors need to either adjust their claims regarding "risk factors" or strengthen their analysis with appropriate multivariate regression techniques to support such claims.
Mainly clear and unambiguous, professional English used throughout, however there are some phrases that should be considered changed, a few spelling mistakes and some grammatical mistakes. Some occurrences of lay English, more academic language is preferred.
Some lines are not easily understood and should be rephrased. The article conforms to professional standards of courtesy and expression.
Literature references should be checked and corrected, as not all references are correct and need to be corrected. Also, the interpretation of some of the referenced articles should be corrected. There is sufficient field background/context provided.
The article has sufficient introduction and background to demonstrate how the work fits into the broader field of knowledge.
The structure of the article conforms to an acceptable format of ‘standard sections’
Figures are relevant to the content of the article, of sufficient resolution. Table 1 and 2 should include numbers (n and N), and should state what values are presented (95% IC?). Table 1 should include the values of all participants. Table 1 should also include a description of the last two columns, as it is not easy for the reader to understand what values are presented. It should clearly state the differences between groups. They are not considered self-contained with relevant results to hypotheses.
All appropriate raw data have been made available in accordance with the Data Sharing policy.
Original primary research is considered within Aims and Scope of the journal.
Research questions are well defined, relevant & meaningful. It is stated how research fills an identified knowledge gap.
The submission defines the research question, which is relevant and meaningful. The knowledge gap being investigated is identified, and statements are made as to how the study contributes to filling that gap.
The investigation is considered conducted rigorously to an adequate technical standard. The research is conducted in conformity with the prevailing ethical standards in the field.
Methods are not satisfactory described as they lack sufficient detail and information to replicate, and the analysis should be more clearly explained. The method is not described sufficiently according to the STROBE checklist, this should be corrected.
As the method is not considered to be satisfactory described it is difficult to evaluate the validity of findings. I also wish the authors would discuss the implication of doing this study on such an early postpartum population. This may increase the risk that postpartum women receive treatment that is not necessary.
I also miss in the discussion that the method is cross-sectional data and limitations this will imply on the results.
I assume that all the underlying data has been provided.
I miss a statement of what their aim for the analyses were, was it prediction or understanding causal mechanisms? What is a risk factor? I am afraid the conclusion is too broad and is not supported by the actual findings.
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