Reviewer ’s report  
 
Title: A preliminary evaluation of influence of body mass index on in vitro fertilization outcome  
in non -obese endometriosis patients. An observational cross -sectional study  
 
Version: 0 Date: 13 Apr 2017  
 
Reviewe r: Paola Vigano  
 
Reviewer's report:  
 
In this study, Garalejic and coworkers have analyzed the impact of higher BMI on IVF outcomes 
in non obese endometriosis women. This on the basis of the evidence that a lower BMI  would be 
a risk factor for the development of endometriosis. This is an observational cross -sectional study 
including 156 infertile laparoscopically -proven endometriosis women. Results obtained would 
indicate that overweight women with endometriosis do no t have better IVF outcomes compared 
to normal and underweight women. On the other hand, there was a non significant trend toward 
an increase of clinical and ongoing pregnancy rates with BMI increase.  
 
The major issue of this paper is that the Authors did no t provide a sample size calculation based 
on a primary endpoint. Therefore, it is highly likely that the study is underpowered. The potential 
clinical message behind this information is very important. However, with this low sample size 
(overweight cases n =29)and the absence of a sample size calculation, the risk is to have 
erroneously failed to detect a difference.  
 
A more reliable message could be obtained including a higher number of patients.  
 
Are the methods appropriate and well described?  
If no t, 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.  
 
Yes 
 
Are the conclusions drawn adequately supported by t he data shown?  
If not, please explain in your comments to the authors.  
 
No 
 
 
 
 
 
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, ple ase specify what aspects require further  
assessment in your comments to the editors.  
 
I recommend additional statistical review  
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Acceptable  
 
 
 
 
Declaration of competing interests  
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3. Do you hold or are you curr ently applying for any patents relating to the content of the  
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holds  or has applied for patents relating to the content of the manuscript?  
 
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below.  If your reply is yes to any, please g ive details below.  
 
I declare that I h ave no competing interests  
 
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