Reviewer ’s report  
 
Title:  Pre-pregnancy body mass ind ex and gestational weight gain and their effects on pregnancy 
and birth outcomes: a cohort study in West Sumatra, Indonesia  
 
Version: 0 Date: 01 Feb 2017 
 
Reviewer:  Kristine  Koski  
 
Reviewer’s report:  
 
This paper has potential as the authors have a robust sample size to provide an in dept h analysis 
of the interrelationships among BMI, GWG and birth outcomes in Sumatra Indonesia. In the 
body of the paper the authors also raise an important issue as to whether IOM BMI cut -offs or 
Asian BMI cut -offs should be used to identify appropriate/inap propriate GWGs with birth weight 
outcomes in this population. This question certainly can be addressed possibly using the 
descriptive statistics in Table 3. However, the data certainly could be used to develop multiple 
and logistic regression models for in appropriate vs appropriate GWGs for different BMI 
categories (Asian?) and for several infant outcomes. Therefore a more complex analytical 
framework would substantially improve the paper and overcome several of its serious 
limitations. The authors need to focus on the development of testable hypotheses and specific 
objectives and then proceed to answer those questions using a more robust statistical analysis 
framework. The paper should not be framed as an exploratory one given the range of important 
data co llected and the potential this data has for answering several important questions with 
regards to maternal BMI, GWG and infant outcomes.  
 
Current limitations of the data presentation are as follows: (1) Table 1 could be simplified to 
emphasize  descriptiv e data and presented in the text as there is no need to present data when 
percentages are small ( <50%); (2) Table 2 as a descriptive Table could be used to frame 
population characteristics, but the authors present an interesting set of data that is not in cluded in 
any of their analyses. Moreover the Table does not include post -hoc analyses or any comparisons 
among the two BMI classifications, if this remains part of their discussion about which 
classification should be used for their population. (3) Table 3 is quite interesting and deserves a 
hypothesis but the ANOVA approach provides only descriptive data for which post - hoc tests are 
required. However multiple logistic and linear regressions could provide a more robust 
interpretation of what appear to be very interesting findings, given the range of variables 
showing differences; (4) Table 5 is a multivariate model but only includes 5 descriptive factors 
when indeed the authors have a plethora of more interesting variables that could be entered in 
their mo dels. Moreover this table only supports inclusion older established determinant whereas 
the addition of some of their unique variables could provide more insight; (5) Table 6 appears to 
be another important descriptive table but it should be combined with earlier descriptive tables. 
A more robust regression analyses for birth weight as the dependent variable could be performed 
are at the end of the paper is puzzling. (6) Figure 1 with comparative statistics could be helpful to 
address the use of IOM vs Asia n BMI categories and FIGURE 2 set up as stacked bar graphs 
side by side could also be used.  However a figure without statistical comparisons is not helpful. 
Finally is appears that slightly >500 women have complete data and therefore the reference to 
1011  women may not be confined to the sample for which they applied their statistical analyses? 
Make it clear to the readers when the full sample size is used and/or when subsets with smaller 
sample sizes are analyzed or settle upon a final sample size for whi ch there is  a complete data 
set and then establish that it is or is not different from your larger sample size.  
 
 
Other comments:  
 
Title: Pattern is not well defined throughout the paper. Moreover throughout the paper the 
authors need to discriminate bette r between the use of increase/decrease which implies change vs 
use of higher/lower were comparing differences between groups.   
 
Abstract is missing hypotheses and specific objectives and its method section does not provide 
information on comparative group s and/or independent variables for regression analyses for 
major outcomes of interest. Results section would need to rewritten following reanalysis, would 
need to include p values and would need to focus on major findings only.  
 
In the methods, a more deta iled statistical framework is required.  
 
The discussion contains a lot of results that were not included in the results section. It also lacks 
the usual summary of significant findings in the first paragraph.  Most of the discussion focuses 
on descriptive  statistics.  Descriptive statistics could all be summarized in one tightly written 
paragraph. The remainder of the discussion needs to reflect a higher level of statistical analyses 
which could be addressed by developing multiple linear and logistic regre ssion models for the 
study.  
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
No 
 
Does the work include the necessary controls?  
If not, please specify which controls are required in your comments to the authors.  
 
Unable to assess  
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the  authors.  
 
Unable to assess  
 
Are you able to assess any statistics in the manuscript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please specify what aspects require further 
assessment in your comments to the editors.  
 
I am able to assess the statistics  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
Declaration of competing interests  
Please complete a declaration o f competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, fees, funding, or salary from an 
organisation that may in any way gain or lose financially from the publication of this 
manuscript, either  now or in the future?  
 
2. Do you hold any stocks or shares in an organisation that may in any way gain or lose 
financially from the publication of this manuscript, either now or in the future?  
 
3. Do you hold or are you currently applying for any patents relating to the content of the 
manuscript?  
 
4. Have you received reimbursements, fees, funding, or salary from an organization that 
holds or has applied for patents relating to the content of the manuscript?  
 
5. Do you have any other financial competing interests?  
 
6. Do you have any non -financial competing interests in relation to this paper?  
 
If you can answer no to all of the above, write 'I declare that I have no competing interests' 
below. If your reply is yes to any, please give details below.  
 
I declare that I have no competing interests.  
 
I agree to the open peer review policy of the journal. I understand that my name will be included 
on my report to the authors and, if the manuscript is accepted for publication, my named report 
including any attachmen ts I upload will be posted on the website along with the authors' 
responses. I agree for my report to be made available under an Open Access Creative Commons 
CC-BY license ( http://creativecommons.or g/licenses/by/4.0/ ). I understand that any comments 
which I do not wish to be included in my named report can be included as confidential comments 
to the editors, which will not be published.  
 
I agree to the open peer review policy of the journal