Review Reports

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for inviting me to review this research on infant postural control and daily activities in pre-term and full-term infants raised in orphanages in Thailand. This was a lovely paper—the authors should be commended for collecting data in a unique sample of infants which I am sure was a tremendous undertaking. The paper was well-written overall and has a nice story about the importance of postural control while sitting and its relations to infants’ daily experiences. Below I raise a few important methodological points and provide some suggestions for ways to improve the manuscript. Some are certainly feasible, but others may not be given current data that the authors have in hand. Please address all issues.

1. Why did the authors choose to do this study in an orphanage rather than pre-term vs. full-term infants in the general community? The rationale was unclear. Please provide additional motivation for this decision. Of course, it is interesting and important work but it was not apparent—from a scientific standpoint—why this was done. Perhaps, the results would have been entirely different (or similar) if this study sampled infants who lived with their birth families.
2. The authors need to provide more detail about how they collected the SATCo. I am familiar with this assessment but most readers are not. Please paint the picture better for the reader. How did the hands contact the baby? How did they move down the body? What did the entire process look like and how was it done? Also, it would be amazing if the authors could include some images (as a new figure) or share a video of the study procedures so readers could see it firsthand.
3. I assume the DAIS was used for simplicity and ease of data collection, but I worry about its ability to capture real differences in behavior. From what I gathered, it is a pencil-and-paper scoring method that happens in real time. How was reliability established among multiple observers in the study? Did everyone choose the same pictures from the list for each 15-min interval or were there inter-observer differences? The authors must explain this process and provide reliability statistics as they did for the SATCo administration.
4. Did the authors collect any video data to validate the DAIS? Moreover, if video was collected, can the authors annotate videos for infant behavior (e.g., time sitting, time crawling, time prone, time feeding) to get more fine-grained measures of their behaviors of interest? This would be the ideal data source for this study.
5. Please share the DAIS as a supplementary material. I could not find it online and this impacted my ability to evaluate its use for this study,
6. Based on my calculations, the authors observed each infant for 25 hours. Is this correct? How many intervals were scored for each infant? The authors must include additional descriptive statistics about this in their results.
7. The group difference in SATCo gives me pause. What was the effect size? I worry about overinterpreting a p-value that is essentially on the borderline of significance without corresponding information about effect size or a Bayesian model that provides additional evidence. I would be very cautious about interpreting significant in the omnibus (overall) measure if none of the individual component measures (static, active, reactive) were also significant. I worry this is a false positive. This is a real issue for the authors and must be addressed.
8. The authors only present the correlations among SATCo and DAIS for the entire sample, but not split by pre-term versus full-term. Why? This further suggests that the there were no meaningful differences in SATCo scores and thus should not be discussed as if there were.
9. The authors must create figures for their data (e.g., frequency distributions, bubble plots, scatter plots, anything). The reader needs to see individual and group data so they can evaluate differences in each distribution. The tables hide the results.
10. The discussion is fine, but I was missing the “big picture” takeaways from this study. The authors spend a lot of time relating their work to prior research and dive into that immediately. However, I would rather have seen a bigger conversation about their implications before a detailed conversation about concordance with prior work.
11. Minor: Everything needs to be in the past tense. This work has already been done. Please fix throughout.

Author Response

Responses to reviewers

Reviewer 1:

Comments and Suggestions for Authors

Thank you for inviting me to review this research on infant postural control and daily activities in pre-term and full-term infants raised in orphanages in Thailand. This was a lovely paper—the authors should be commended for collecting data in a unique sample of infants, which I am sure was a tremendous undertaking. The paper was well-written overall and has a nice story about the importance of postural control while sitting and its relation to infants’ daily experiences. Below I raise a few important methodological points and provide some suggestions for ways to improve the manuscript. Some are certainly feasible, but others may not be given current data that the authors have in hand. Please address all issues.

Response to reviewer:

Thank you very much for your thoughtful and encouraging comments on our manuscript. We sincerely appreciate your recognition of our efforts in conducting this study. Your detailed feedback and methodological suggestions are invaluable to us. We will carefully consider and address each point you raised to strengthen the clarity, rigor, and overall quality of our paper.

Reviewer’s comments

1. Why did the authors choose to do this study in an orphanage rather than pre-term vs. full-term infants in the general community? The rationale was unclear. Please provide additional motivation for this decision. Of course, it is interesting and important work but it was not apparent—from a scientific standpoint—why this was done. Perhaps, the results would have been entirely different (or similar) if this study sampled infants who lived with their birth families.

 

Response to reviewer:

 

The authors conducted research on segmental trunk control in premature and full-term infants raised in an orphanage because limited data on trunk control in this population were available. We are collaborating to stimulate infants’ development, especially gross motor development, from newborn to 18 months at the orphanage. The child-rearing practices and the institution's environment differ from those of family child-rearing routines and home environments; the authors, therefore, assume that the results would vary. Investigating segmental trunk control in these infants helps us understand how their trunk control developed. We encourage caregivers to learn and modify routines to stimulate children’s development.  

 

We add a rationale for conducting a study on segmental trunk control in orphaned infants on page 2.

 

 

Reviewer’s comments

1. The authors need to provide more detail about how they collected the SATCo. I am familiar with this assessment but most readers are not. Please paint the picture better for the reader. How did the hands contact the baby? How did they move down the body? What did the entire process look like and how was it done? Also, it would be amazing if the authors could include some images (as a new figure) or share a video of the study procedures so readers could see it firsthand.

 

Response to reviewer:

We added more details and a picture of the SATCo test in an infant on page 4.

 

Reviewer’s comments

1. I assume the DAIS was used for simplicity and ease of data collection, but I worry about its ability to capture real differences in behavior. From what I gathered, it is a pencil-and-paper scoring method that happens in real time. How was reliability established among multiple observers in the study? Did everyone choose the same pictures from the list for each 15-min interval or were there inter-observer differences? The authors must explain this process and provide reliability statistics as they did for the SATCo administration.

 

Response to reviewer:

 

The DAIS is a standard tool using a pencil-and-paper scoring method to observe daily activity in real time. It was performed during the day by a single researcher throughout the current study. Because the researcher observed during the daytime for 5 days a week (weekdays and weekends), while the caregivers varied. One limitation of our study was that we did not examine intra-rater and inter-rater reliability of the DAIS. This is our first time using the DAIS, so the researcher practiced using the tool during infant observations for one month before data collection.

 

We also added our study limitations on page 12 line 445-448.

 

Reviewer’s comments

1. Did the authors collect any video data to validate the DAIS? Moreover, if video was collected, can the authors annotate videos for infant behavior (e.g., time sitting, time crawling, time prone, time feeding) to get more fine-grained measures of their behaviors of interest? This would be the ideal data source for this study.

 

Response to reviewer:

We sincerely appreciate the suggestion regarding the use of video data. While we do not have recorded videos, we have collected images and detailed time logs of the infants' activities, such as sitting, crawling, and feeding. These time logs include the duration of each activity, specifying start and end times, enabling us to analyze the infants' daily routine more comprehensively. Although video is considered the ideal method, we believe that combining images and time logs still provides valuable insights for our research.

Reviewer’s comments

1. Please share the DAIS as a supplementary material. I could not find it online and this impacted my ability to evaluate its use for this study.

 

Response to reviewer:

Thank you very much. I would be happy to share the DAIS as supplementary material.

 

Reviewer’s comments

1. Based on my calculations, the authors observed each infant for 25 hours. Is this correct? How many intervals were scored for each infant? The authors must include additional descriptive statistics about this in their results.

 

Response to reviewer:

Yes, as described, we observed each infant for a total of 25 hours over 5 days. We marked one block for each 15-minute interval for various activities such as feeding, bathing, dressing, carrying, quiet play, active play, and sleeping. Therefore, the total number of intervals for that day will depend on how many blocks we recorded for each activity. However, some activities, such as diaper changes, lasted less than 15 minutes. To address the variability in activity duration, we used the formula:

Score = (Duration of Activity in Minutes / 15) × Category Value.

Because DAIS is an interval-based system, the Total DAIS Score reflects the total number of 15-minute observation intervals, including proportional intervals for shorter activities. Although the original interval sheets are no longer available, the Total DAIS Scores provide an accurate estimate of the total observation blocks for each infant. Figure 2 on pages 8 shows the distribution of these scores, demonstrating the range of observed intervals and confirming that infants received consistent coverage aligned with the planned 25-hour protocol.

 

Reviewer’s comments

1. The group difference in SATCo gives me pause. What was the effect size? I worry about overinterpreting a p-value that is essentially on the borderline of significance without corresponding information about effect size or a Bayesian model that provides additional evidence. I would be very cautious about interpreting significant in the omnibus (overall) measure if none of the individual component measures (static, active, reactive) were also significant. I worry this is a false positive. This is a real issue for the authors and must be addressed.

 

Response to reviewer:

Thank you for raising this important concern. In response to your comment, we calculated the effect size of the group difference in the SATCo total score. Using the formula r = Z / √N, the effect size was r = –0.349, which corresponds to a small-to-medium effect according to Cohen’s criteria. This indicates that although the difference reached statistical significance, the effect is modest and should be interpreted cautiously.

To further assess the strength of the evidence, we conducted a Bayesian Mann–Whitney analysis. The Bayes factor (BF₁₀ = 1.035) indicates only anecdotal evidence for a group difference, meaning that the data do not clearly favor either the null or the alternative hypothesis. This aligns with the reviewer’s concern about potential borderline significance.

We also note that none of the individual SATCo components (static, active, reactive) were significant, suggesting that the difference in the total score likely reflects small contributions across multiple domains rather than a strong effect in any single component.

Accordingly, we revised the Results (Page 8 line 287-290) and the Discussion (Page 11 line 418-420) to provide a more cautious, preliminary interpretation of the group difference in total SATCo score. We appreciate the reviewer’s guidance in ensuring a balanced and non-overstated interpretation.

 

Reviewer’s comments

1. The authors only present the correlations among SATCo and DAIS for the entire sample, but not split by pre-term versus full-term. Why? This further suggests that the there were no meaningful differences in SATCo scores and thus should not be discussed as if there were.

 

Response to reviewer:

Thank you for your valuable comment. We did not present the correlation between SATCo and DAIS with a comparison for the two groups in Table 6 because both groups were cared for by the same set of caregivers, and we expected their daily activities to be broadly similar. Our primary focus was to compare the infants’ SATCo scores while they were living in the same environment. As noted in the revised Discussion, although a statistically significant difference in SATCo scores was observed, we have explained that the small-to-medium effect size and anecdotal Bayesian evidence indicate that the lack of clinical difference in SACTo score (Page 11 line 418-420)

 

Reviewer’s comments

1. The authors must create figures for their data (e.g., frequency distributions, bubble plots, scatter plots, anything). The reader needs to see individual and group data so they can evaluate differences in each distribution. The tables hide the results.

 

Response to reviewer:

Thank you very much for the suggestion. We have added a box plot on page 8 and a dot plot on page 8.

Reviewer’s comments

1. The discussion is fine, but I was missing the “big picture” takeaways from this study. The authors spend a lot of time relating their work to prior research and dive into that immediately. However, I would rather have seen a bigger conversation about their implications before a detailed conversation about concordance with prior work.

 

Response to reviewer:

Thank you very much for the suggestion. We have added implications of the study and reorganized the paragraph in the discussion on from page 9.

 

Reviewer’s comments

1. Minor: Everything needs to be in the past tense. This work has already been done. Please fix throughout.

Response to reviewer:

Thank you very much for your suggestion. We have revised the text and will have a language edit.

Reviewer 2 Report

Comments and Suggestions for Authors

Major Points

Please acknowledge explicitly that the sample size fell short of the calculated requirement, and discuss how this may affect statistical power.

Provide a more thorough discussion of confounding prenatal factors (maternal substance use, maternal mental illness), which were unequally distributed across groups.

Clarify the clinical significance of differences in SATCo scores. Do the numerical differences reflect meaningful motor function differences?

Strengthen the limitations section: cross-sectional design, absence of infants raised in family environments, single orphanage setting, and lack of DAIS reliability testing.

Moderate the conclusions regarding environmental impacts; avoid causal language. Frame findings as associations.

Discuss potential methodological overlap contributing to the high correlation between SATCo and DAIS.

Minor Points

Streamline the introduction by reducing repeated arguments.

Shorten the abstract by focusing on key results and limitations rather than methodological detail.

In the discussion, more clearly distinguish between observed findings and hypothetical recommendations.

Consider presenting practical recommendations for orphanage practices (e.g., structured upright play, varied positioning) in a dedicated paragraph separate from research conclusions.

Comments for author File: Comments.pdf

Author Response

Reviewer 2

Comments and Suggestions for Authors

Major Points

Reviewer’s comments

1. Please acknowledge explicitly that the sample size fell short of the calculated requirement, and discuss how this may affect statistical power.

Response to reviewer:

Thank you very much for the suggestion. The final sample sizes (16 and 17 infants per group) fell slightly short of the target of 17 per group indicated by the a priori power calculation; this shortfall was unlikely to have substantially reduced statistical power. A somewhat smaller sample may modestly increase the risk of Type II error, particularly for detecting small effects, and this may partly explain the absence of pronounced differences across the SATCo components.

We added the explanation in the discussion on page 11, lines 420-423.

 

Reviewer’s comments

2. Provide a more thorough discussion of confounding prenatal factors (maternal substance use, maternal mental illness), which were unequally distributed across groups.

Response to reviewer:

Thank you for pointing this out. We added and rewrote the discussion part on page 11 line 428-430.

 

Reviewer’s comments

3. Clarify the clinical significance of differences in SATCo scores. Do the numerical differences reflect meaningful motor function differences?

Response to reviewer:

Although the total SATCo score differed statistically between groups, the clinical meaning of this difference should be interpreted with caution, as the significance was not pronounced. The score difference suggests that full-term infants may have slightly better stability during upright sitting, especially in maintaining posture without additional support. This difference is relatively small and does not represent a shift from impaired to fully functional control; both groups continued to show limited reactive control. Therefore, while the numerical difference indicates a modest functional advantage for full-term infants, it is unlikely to indicate the substantial differences in their everyday motor performance.

We added the data analyses and more details in the results (page 8 line 291) and the discussion part (page 9).

 

Reviewer’s comments

4. Strengthen the limitations section: cross-sectional design, absence of infants raised in family environments, single orphanage setting, and lack of DAIS reliability testing.

Response to reviewer:

Thank you very much for the suggestion. We have rewritten the limitations part on page 12.

 

Reviewer’s comments

5. Moderate the conclusions regarding environmental impacts; avoid causal language. Frame findings as associations.

Response to reviewer:

We appreciate this important point. In the revised manuscript, we have moderated all statements that previously implied causality. Given the cross-sectional design, we cannot infer that environmental conditions directly caused differences in trunk control.

 

Reviewer’s comments

6. Discuss potential methodological overlap contributing to the high correlation between SATCo and DAIS.

Response to reviewer:

Thank you very much for the suggestion. We added the explanation in the discussion on page 9 line 329.

 

Minor Points

Reviewer’s comments

1. Streamline the introduction by reducing repeated arguments.

Response to reviewer:

Thank you for this helpful suggestion. We have revised the Introduction part to remove repeated arguments and consolidate overlapping statements.

 

Reviewer’s comments

2. Shorten the abstract by focusing on key results and limitations rather than methodological detail.

Response to reviewer:

Thank you very much for the suggestion, we improved the abstract on the first page.

 

Reviewer’s comments

3. In the discussion, more clearly distinguish between observed findings and hypothetical recommendations.

Response to reviewer:

Thank you very much for the suggestion.  We have rewritten the discussion section.

 

Reviewer’s comments

4. Consider presenting practical recommendations for orphanage practices (e.g., structured upright play, varied positioning) in a dedicated paragraph separate from research conclusions.

Response to reviewer:

Thank you very much for the suggestion. We added recommendations for the orphanage on page 12, line 454.

Round 2

Reviewer 2 Report

Comments and Suggestions for Authors

All previously raised comments have been fully and appropriately addressed; I have no further remarks at this stage.