PONE-D-20-31154

Birth month and infant gross motor development – Results from the Japan Environment and Children’s Study (JECS)

PLOS ONE

Dear Dr. Suganuma,

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Maria Christine Magnus, MPH

Academic Editor

PLOS ONE

Additional Editor Comments:

We have received comments on your manuscript from two reviewers. I also have additional comments on your paper. Please address all comments carefully in your revised manuscript.

Comments:

1) Please clearly justify the cut-off values you have used for the neurodevelopmental scores.

2) You need to state how you dealt with missing information. Specifically, I assume that there was missing information in at least some of the covariates you adjusted for in the multivariable analysis. If there was no missing in the covariates, then this should be stated. If there was missing information, then you should consider multiple imputation.

3) Some of the covariates you adjusted for are likely to be mediators (potentially part of the explanatory pathway) and not confounders. I am for example thinking of all the pregnancy outcomes which you adjust for. You should clearly classify which covariates are confounders as opposed to potential mediators. You should also not adjust your main model for the potential mediators but include these in a second multivariable model.

4) I wonder why you chose to look at season of delivery and not season of conception? Since you mention that intra uterine vitamin D levels during the fist trimester might be part of the explanatory mechanism, I wonder if season of conception is not of more interest? Please carefully think this through and justify your decision.

5) Move all results from the methods to the results section. There should be no results tables or references to these in the methods.

6) The manuscipt would greatly benefit from language editing. I strongly suggest you consider sending the mansucript for professtional language editing.

7) Please clarify why you chose to use poission regression (IRR) instead of a log-binomial regression (RR)?

Journal Requirements:

When submitting your revision, we need you to address these additional requirements.

1.) Please ensure that your manuscript meets PLOS ONE's style requirements, including those for file naming. The PLOS ONE style templates can be found at

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2.) Thank you for including your ethics statement:  "The JECS protocol was reviewed and approved by the Ministry of the Environment’s Institutional Review Board on Epidemiological Studies and by the Ethics Committees of all participating institutions. Written informed consent was obtained from all

participating women and men. The below link contains the JECS ethical information (p17)

. " ext-link-type="uri" xlink:type="simple">http://www.nies.go.jp/kanko/news/38/38-4/jqjm1000000i2db3-att/jqjm1000000i2dc0.pdf".   

Please amend your current ethics statement to include the full name of the ethics committee/institutional review board(s) that approved your specific study.

Once you have amended this/these statement(s) in the Methods section of the manuscript, please add the same text to the “Ethics Statement” field of the submission form (via “Edit Submission”).

For additional information about PLOS ONE ethical requirements for human subjects research, please refer to http://journals.plos.org/plosone/s/submission-guidelines#loc-human-subjects-research.

3.) In statistical methods, please clarify whether you corrected for multiple comparisons.

4.) Thank you for stating the following in the Acknowledgments Section of your manuscript:

'The Japan Environment and Children’s Study was funded by the Ministry of Environment, Japan.'

We note that you have provided funding information that is not currently declared in your Funding Statement. However, funding information should not appear in the Acknowledgments section or other areas of your manuscript. We will only publish funding information present in the Funding Statement section of the online submission form.

Please remove any funding-related text from the manuscript and let us know how you would like to update your Funding Statement. Currently, your Funding Statement reads as follows:

'The authors received no specific funding for this work.'

Please include your amended statements within your cover letter; we will change the online submission form on your behalf.

5.) One of the noted authors is a group or consortium Japan Environment and Children’s Study Group. In addition to naming the author group, please list the individual authors and affiliations within this group in the acknowledgments section of your manuscript. Please also indicate clearly a lead author for this group along with a contact email address.

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Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

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2. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

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3. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

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4. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

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5. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: Abstract:

-It is appropriate to mentioned P values in significant result.

Methods:

-The following phrase, Fig 1, Table 1, 2 and 3 which is given in the statistical analysis section, should be given in the results section.

“The means of maternal age at enrolment for the study subjects and 81 the excluded were 30.8 (95% CI: 30.0, 30.9) and 30.3 (95% CI: 30.2, 30.3) years old”

Discussion:

In methods section mentioned:

-“The questionnaires covered various topics, including lifestyle, socio-economic status (SES), diet, medical history, and medication”.

And in Table 1, many independent variables were mentioned in the study cases, such as prepregnancy BMI, hyperbilirubinemia, Apgar score, C-section, which there were significant difference. But in the discussion, there is no mention of the possibility of the effect of the independent variables.

Some abbreviations need to be mentioned in full wherever they are first mentioned: EPDS, MR, LD.

Figure 2 is not clear.

Reviewer #2: Introduction.

The study needs more information on previous findings on relationship between birth month and gross motor skills in early childhood, even the previous findings were not from large cohort samples. What has the literature found? Has the literature found significantly positive/negative relationship between the two variables of interest? Has any literature investigated the trajectories of motor development of young children? I think it needs to add more motivations of the study in this section.

Methods.

1. What’s the strategies of the sampling? What’s the process of data collection? Such as data on vitamin D intake, etc. Readers may want to know more detailed information on sampling and data collection.

2. As the measurement of child gross motor development, how about the internal consistency of the ASQ-3 for the sample used in the study? I would suggest the authors reporting this in the methods section.

Results.

1. Table 1 looks too big. And it was inserted in the wrong place of the manuscript. It is also true for Tables 2 3.

2. On line 173, a quotation mark has been missed.

Discussion.

1. Again, more literature should be revisited in this section regarding to the issues that are discussed here.

2. What are the implications of the study? The implications should be discussed here or in the conclusion section.

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Reviewer #1: No

Reviewer #2: No

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Attachments

Attachment

Submitted filename: Comments.docx

Birth month and infant gross motor development: Results from the Japan Environment and Children’s Study (JECS)

PONE-D-20-31154R1

Dear Dr. Suganuma,

We’re pleased to inform you that your manuscript has been judged scientifically suitable for publication and will be formally accepted for publication once it meets all outstanding technical requirements.

Within one week, you’ll receive an e-mail detailing the required amendments. When these have been addressed, you’ll receive a formal acceptance letter and your manuscript will be scheduled for publication.

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Kind regards,

Maria Christine Magnus, MPH

Academic Editor

PLOS ONE

Additional Editor Comments (optional):

Reviewers' comments:

Reviewer's Responses to Questions

Comments to the Author

1. If the authors have adequately addressed your comments raised in a previous round of review and you feel that this manuscript is now acceptable for publication, you may indicate that here to bypass the “Comments to the Author” section, enter your conflict of interest statement in the “Confidential to Editor” section, and submit your "Accept" recommendation.

Reviewer #1: All comments have been addressed

Reviewer #2: All comments have been addressed

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2. Is the manuscript technically sound, and do the data support the conclusions?

The manuscript must describe a technically sound piece of scientific research with data that supports the conclusions. Experiments must have been conducted rigorously, with appropriate controls, replication, and sample sizes. The conclusions must be drawn appropriately based on the data presented.

Reviewer #1: Yes

Reviewer #2: Yes

**********

3. Has the statistical analysis been performed appropriately and rigorously?

Reviewer #1: Yes

Reviewer #2: Yes

**********

4. Have the authors made all data underlying the findings in their manuscript fully available?

The PLOS Data policy requires authors to make all data underlying the findings described in their manuscript fully available without restriction, with rare exception (please refer to the Data Availability Statement in the manuscript PDF file). The data should be provided as part of the manuscript or its supporting information, or deposited to a public repository. For example, in addition to summary statistics, the data points behind means, medians and variance measures should be available. If there are restrictions on publicly sharing data—e.g. participant privacy or use of data from a third party—those must be specified.

Reviewer #1: Yes

Reviewer #2: Yes

**********

5. Is the manuscript presented in an intelligible fashion and written in standard English?

PLOS ONE does not copyedit accepted manuscripts, so the language in submitted articles must be clear, correct, and unambiguous. Any typographical or grammatical errors should be corrected at revision, so please note any specific errors here.

Reviewer #1: Yes

Reviewer #2: Yes

**********

6. Review Comments to the Author

Please use the space provided to explain your answers to the questions above. You may also include additional comments for the author, including concerns about dual publication, research ethics, or publication ethics. (Please upload your review as an attachment if it exceeds 20,000 characters)

Reviewer #1: The revised manuscript is acceptable. The authors have adequately addressed my comments raised in a previous round of review and I feel that this manuscript is now acceptable for publication.

Reviewer #2: All my comments have been addressed. The format and the language of the manuscript now are suitable for publication.

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7. PLOS authors have the option to publish the peer review history of their article (what does this mean?). If published, this will include your full peer review and any attached files.

If you choose “no”, your identity will remain anonymous but your review may still be made public.

Do you want your identity to be public for this peer review? For information about this choice, including consent withdrawal, please see our Privacy Policy.

Reviewer #1: No

Reviewer #2: No