NOTICE

Would consider including something about the comparison between singletons and twins (or even monochorionic and dichorionic singletons and twins), as this is a strength of the study. Evidence for this is that there is no information on the ethnicity/race of the women in the study group. The onus is on the Authors to demonstrate that the intermediate result sets are representative of the original sets.

Putting the results in the form of an effect size makes the result of the statistical test more clinically relevant. The same information should be included in the Materials and Methods section of the manuscript. Please write or paste the page numbers where each item appears in the margin of the checklist.

If the use of the reVITALize definitions is problematic, please discuss this in your point-by-point response to this letter. Abbreviations and acronyms must be spelled out the first time they are used in the abstract and again in the manuscript itself. Putting the results in the form of an effect size makes the result of the statistical test more clinically relevant and provides better consistency than citing P values ​​alone.

If this is based on a systematic literature search, this search should be described in the text (search engine, search terms, search time range and languages ​​covered by the search).

We removed subheadings in the discussion section

P Values vs Effect Size and Confidence Intervals

We described crude ORs and 95% CI as appropriate in the revised

Line 73: ACS is standard of care in US for expected delivery within 7 days at 34 weeks or less but not up to 37 weeks. Not everyone has embraced the ALPS trial use of late preterm

Thank you for your suggestion. As you and another reviewer suggested, we have amended the sentence (Line 74)

Thank you for your comment. We deleted these words (Line 88)

Line 89: As with the abstract notation, please define short- and medium-term time frames you used

As your comment #2, we defined short- and medium-term in the manuscript (Line 90-91)

We apologize for this error, and we have corrected the sentence (Line 99- 100)

According to the guidelines for perinatal care 8 th edition published 2017, the level of NICU in the USA is very similar to that of Japan. We described this in the

Line 104: Is higher order triplets and more? Please clarify

Thank you for your comment. We fixed Figure 1 and the manuscript (Line 103-104)

Who enters data into this database? How is it validated?

Thank you for the questions. Doctors or medical staff enter clinical information into this database with use of a standard network database operation

Please explain how the data for the 3 year child hood status was obtained

Line 119: Defined or define? Have these guidelines changed?

We removed the virgule in the manuscript and tables

• Line 135: Have you spelled out RDS previously? If not, please do so here

We have spelled out RDS in Line 79

• Line 139: What do you mean “clinical syndromes”?

We apologize to use a wrong word. Neonatal sepsis was defined as clinical

• Line 142: Were the psychological tests done by the child’s local pediatrician and reported to the data base or were the children brought to a centralized location for testing?
• As response #11, the psychological tests were performed by experienced clinical assessors around 36 months of age at each facility (Line 139-141)
• Statistics: The statistical editor and one of your reviewers provide a great deal of feedback
• We carefully reviewed the statistical editor and reviewers comments
• Line 176: How was chorionicity assigned?
• Thank you for your valuable comment. As you pointed out, our study showed increased incidence of CLD and home oxygen therapy in the ASC group in

As you pointed out, our study showed increased incidence of CLD and home oxygen therapy in the ASC group in an increased incidence of CLD and home oxygen therapy in the ASC group in singletons, but not in twins.

Obstet). This can be attributed to the fact that improved survival rate by ACS treatment might increase the number of severe/serious neonates requiring prolonged mechanical

• We apologize for these errors. We fixed the manuscript and tables
• Thank you for your comment. As your suggestion, we first discussed the
• Line 273: Delete “So far”
• We deleted it
• Lines 290-292: are you making these as possible explanations in general or is it true in your data set that these differences between groups existed? Does your data base have this
• Thank you for your comment. We fixed the sentence (Line 267-268)
• Line 311: What ethical concerns if it’s unclear if ACS is beneficial to twins?
• We agree with your opinion. We deleted the sentence
• We agree with your comment. We fixed the sentence (Line 302)
• Please edit your Figure 2 to use colors rather than shading differences for the different gestational ages. It’s easier to interpret and does not cost you anything
• Thank you for your valuable suggestion. We uploaded a new version using solid colors

This is consistent with a previous study that used the same database within a different time period. Miyazaki K, 2015, Arch Gynecol. Obstet). This may be attributed to the fact that improved survival with ACS treatment could increase the number of severe/severe neonates requiring long-term mechanical treatment. Does your database have this data set showing that these differences existed between groups?

It is not clear what this sentence is being compared to: it seems as if you are stating the odds ratio. It is not clear what this sentence is comparing: it reads as if you are providing information about patients who delivered only by caesarean section. You should only have 1 OR to determine if the RDS differed between those with and without labor, but you provide 2 different ORs.

REVIEWER COMMENTS

Response to Reviewer #1 comments

What matching algorithm was used? Greedy matching? Nearest neighbor matching?

Thank you for your comment. We apologize for insufficient data

Thank you for your valuable comment as a biostatistician. We rephrased the sentence (Line 92-93)

• It's not clear to me exactly how the interaction was done. Did they pool everyone into a conventional model, or did they maintain the matching and included the interaction term of
• similarly, regarding figure 2, did the authors test for effect modification by gestational age with interaction terms? That's the preferred way, but maybe I missed what was done when I

Figure 2 showed the prevalence of neonatal complications stratified by gestational weeks without adjustment of covariates. We described in the method section

• was there any quality control in the data? That is, did someone go to the original medical records to verify a sample for accuracy of coding of, say, hypertensive

That is, did someone go to the original medical records to verify a sample for accuracy of coding of, say, hypertensive records to verify a sample for accuracy of coding of, say, hypertensive. As we answered (editor comment #10), physicians or medical personnel enter clinical information into this database using a physicians or medical personnel enter clinical information into this database using a standard network database operations manual on a annual basis.

Thank you for your comment. We compared the characteristic and

I see a major problem with how kids got into the database itself. The inclusion criteria

In the early 1990s, Cody Arnold and Michael Kramer published a paper in Am J Epidemiol pointing out that the average weight at 32 weeks is now >1500 grams. Essentially, this means that the cutoff will probably allow all babies <28 weeks, but as gestational age advances, the 1500 gram cutoff means that an increasing number of babies included are already IUGR. And since twins tend to be smaller than singletons, especially after about 26 weeks, more twins than singletons will be allowed in the group.

The only way to solve this problem is to base inclusion on gestational age, regardless of birth weight. The authors should absolutely read Arnold's article and decide whether it invalidates their entire study, and if not, what its impact on the results might be. Thus, approximately 25% of infants born after 30 gestational weeks and 50–75% of infants born after 31 gestational weeks were not eligible for this study.

As you pointed out, the ideal inclusion criteria for this database is based on gestational age regardless of birth weight. We cannot rule out the possibility that this inclusion criterion introduces bias and affects the results to some extent. However, the inclusion criteria of the NRNJ database are similar to other neonatal network databases in Italy, Israel and Spain.

That's because in a trial, one would take women at high risk of preterm birth (at <32 weeks) in the next week and randomize them to ACS or. However, at least some of those random women won't give birth in the next week, and may actually go 32 weeks or even make it all the way. However, with intent to treat, you will need to include those pregnancies in your study evaluation.

However, because this study was based on premature babies, the women who managed to remain pregnant past 32 weeks are by definition excluded, which is a gross violation of intention-to-treat. If, in the hypothetical trial, steroids did not affect time to delivery, this error would lead to random misclassifications or loss of generalizability.

Thank you for your valuable comment. We rephrased the sentence (Line 92-93)

• how often was chorionicity missing?

368 cases were missing. Approximately 5%

Thank you for your comment. We agree with you and other reviewers’

Thank you for your comment. As your suggestion, we emphasized on the outcomes with the lack of significant interaction

Response to reviewer #2

Title. Would consider including something about the comparison between singletons and twins (or even singletons and monochorionic and dichorionic twins), as this is a strength of

Antenatal Corticosteroids and Outcomes in Preterm Twins” would be better

Abstract. The abstract summarizes the manuscript well

Introduction. This section is well written and appropriate in length and content

The Cochrane review was published two years after the WHO recommendations (the WHO did not have the benefit of the Cochrane review when making their recommendations).

Thank you for your information. We added information on published year for readers (Line 78 and 82)

• Methods. Clearly presented
• Results

If the former, please provide all available mid-term performance data (for those that had short-term data). Low follow-up rate at 3 years of age was due to lack of follow-up. We described this limitation in the discussion section due to loss to follow-up.

Discussion

Response 7c: Thank you for your comment. We deleted the sentence to avoid duplication

Figures and tables. Complete, straightforward to follow

Response: Thank you

Response to reviewer #3

This is a rather homogeneous Japanese population and therefore it would be difficult to use any study conclusions to other populations. Evidence for this is that there is no information

The study time period is a bit broad but I do not believe that there was anything of

Thank you

• Because of the complexity of their statistical approach I recommend consultation with a statistician to evaluate the correctness of their analysis

In addition, we carefully reviewed statistical editor and another statistical reviewer’s comments

Several minor spelling or in order. And lines to 225 and 287 the word incubation was used when I believe it should be intubation

We apologize the error. We fixed the word

• The paper entitled "Antenatal Betamethasone for Women at Risk for Late Preterm

Response to STATISTICAL EDITOR COMMENTS

At the outset, we must apologize for not being able to describe the detailed SP matching method in the previous version. We used Greedy nearest neighbor matching without replacement and used one-to-one pairwise matching in this study. A caliper width of 0.2 log standard deviation of the propensity score was used for the developed propensity score, as previously recommended (Austin Pharm statistics, 2011).

Although about 29-34% of singletons and twins were. excluded by PS matching, we used optimal caliper widths for ideal PS matching. Even if we can change the caliper width >0.2 to include more singletons and twins, there is a possibility that we can change the caliper width >0.2 to include more singletons and twins. There is a risk of a larger standardized difference, which could influence different outcomes. Another potential problem is the decrease in the number of participants from the short-term results to the medium-term results (~50% loss of respondents in each subgroup).

The matching at the time of the short-term analysis does not guarantee that the medium-term cohorts are also well matched. We analyzed the baseline characteristics and outcomes between cases with medium-term outcomes and cases without medium-term outcomes (Supplementary Tables 5 and 6).

We found that there are several statistically significant differences between the two groups. However, the differences considered to be small in clinical situation

Even though we consulted with specialists for statistics of our co-authors, we could not

Response: We uploaded a new version of Figure 1 with details of all incomplete data

We needed to use only cases with complete maternal data to perform PS matching and for improvement of data reliability. In addition, as many as 13 variables were included

Response to EDITORIAL OFFICE COMMENTS

• The Editors of Obstetrics & Gynecology are seeking to increase transparency around its peer-review process, in line with efforts to do so in international biomedical peer review
• OPT-OUT: No, please do not publish my point-by-point response letter
• OPT-IN: Yes, please publish our point-by-point response letter
• We have confirmed this with co-authors
• Our journal requires that all evidence-based research submissions be accompanied by a transparency declaration statement from the manuscript's lead author. The statement is as
• We included this statements in our cover letter. And we uploaded the signed transparency declaration
• In order for an administrative database study to be considered for publication in Obstetrics
• Doctors or medical staff enter clinical information into this database with use of a standard network database operation manual on a yearly basis. Basically, data
• Please submit a completed STROBE checklist with your revision
• We included the STROBE checklist at the end of this letter
• Standard obstetric and gynecology data definitions have been developed through the reVITALize initiative, which was convened by the American College of Obstetricians and
• We followed the reVITALize definitions in this study
• Because of space limitations, it is important that your revised manuscript adhere to the following length restrictions by manuscript type: Original Research reports should not exceed
• Our manuscript is 22 pages long without references (4,970 words without references)
• Specific rules govern the use of acknowledgments in the journal. Please note the following guidelines
• All of the above have been included on the title page of the manuscript
• We removed the causal language from Precis and other sections
• The most common deficiency in revised manuscripts involves the abstract. Be sure there are no inconsistencies between the Abstract and the manuscript, and that the Abstract has a
• The abstract matches the body of the manuscript and follows the journal guideline
• Only standard abbreviations and acronyms were used in the manuscript
• We have removed all used of the virgule symbol throughout the text and tables
• In your Abstract, manuscript Results sections, and tables, the preferred citation should be in terms of an effect size, such as odds ratio or relative risk or the mean difference of a
• We described OR and 95% CI as appropriate in the revised manuscript
• Line 311: We discourage claims of first reports since they are often difficult to prove
• Thank you for your comment. We deleted the words
• Please review the journal's Table Checklist to make sure that your tables conform to journal style. The Table Checklist is available online here
• We have reviewed this checklist and updated out tables accordingly
• The American College of Obstetricians and Gynecologists' (ACOG) documents are frequently updated. These documents may be withdrawn and replaced with newer, revised
• We understand
• Figure
• We uploaded a new version using solid colors as bars
• Authors whose manuscripts have been accepted for publication have the option to pay an
• We understand
• Yes, revision of the manuscript has been approved by all co-authors
• Objectives 3 State specific objectives, including any prespecified hypotheses 5
• Bias 9 Describe any efforts to address potential sources of bias 6

Check with your co-authors that the disclosures listed in their eCTA forms are properly disclosed on the cover page of the manuscript. Our journal requires that all evidence-based research be accompanied by a transparency statement from the manuscript's lead author. The statement is as follows: "The lead author* certifies that this manuscript is a fair, accurate and transparent representation of the study being reported; that no important aspect of the study has been omitted;.

In your reply, please tell us who entered the data and how the accuracy of the database was verified. Be sure to indicate in your cover letter that you have followed the CONSORT, MOOSE, PRISMA, PRISMA for harms, STARD, STROBE, CHEERS, SQUIRE 2.0 or CHERRIES guidelines, as applicable. Standard Obstetrics and Gynecology Data Definitions were developed by the reVITALize Initiative convened by the American College of Obstetricians and the reVITALize Initiative convened by the American College of Obstetricians and Gynecologists and members of the Women's Health Registry Alliance.

All persons who contributed to the work reported in the manuscript, but not sufficiently to be authors, should be acknowledged. Written permission should be obtained from all individuals named in the acknowledgements, as readers may infer that they endorse the data and conclusions. Please note that your response to the journal author electronic form verifies that permission has been obtained from all persons named.

If all or part of the paper was presented at the annual clinical and scientific meeting of the American College of Obstetricians and Gynecologists or at any other organizational meeting, note should be taken of that presentation (include the exact dates and location of into the meeting). Make sure that there are no inconsistencies between the abstract and the manuscript, and that the abstract is a There are no inconsistencies between the abstract and the manuscript, and that the abstract has a clear conclusion statement based on the results found in the paper is. Make sure that the summary does not contain information that is not in the main text.

If you cite ACOG documents in your manuscript, please ensure that the reference you cite is still current and available. If the reference you're citing has been updated (ie, replaced by a newer version), make sure the new version supports the statement you're making in your manuscript, and then update your reference list accordingly. exceptions may include manuscripts dealing with objects of historical interest). In most cases, if an ACOG document has been retracted, it should not be referenced in your manuscript (exceptions may include manuscripts dealing with topics of historical interest).

If you submit a revision, we will assume that it was developed in consultation with your co-authors and that each author has given approval for the final form of the revision. Page No Title and abstract 1 (a) Indicate the study's design with a commonly used term in the. b) In the summary, give an informative and balanced summary of what was done and what was found.