Reviewer ’s report  
 
Title: Nocturnal finger skin temperature in menstrual cycle trackin g: Ambulatory pilot study 
using a wearable Oura ring  
 
Version: 0 Date: 20 Feb 201 9 
 
Reviewer: Reviewer 2  
 
Reviewer's report:  
PEER REVIEWER ASSESSMENTS:  
 
OBJECTIVE - Full research articles: is there a clear objective that addresses a testable research 
question(s) (brief or other article types: is there a clear objective)?  
Yes - there is a clear objective  
 
DESIGN - Is the current approach (including controls and analysis protocols) appropriate for the 
objective?  
No - there are major issues  
 
EXECUTION - Are the experiments and analyses performed with technical rigor to allow 
confidence in the results?  
No - there are major issues  
 
Statistics - Is the use of statistics in the manuscript appropriate?  
Yes - appropriate statistical analyses have been used in the study  
 
INTERPRETATION - Is the current interpretation/discussion of th e results reasonable and not 
overstated?  
No - there are major issues  
 
OVERALL MANUSCRIPT POTENTIAL - Is the current version of this work technically 
sound? If not, can revisions be made to make the work technically sound?  
Maybe - with major revisions  
 
PEER  REVIEWER COMMENTS:  
GENERAL COMMENTS: The information provided is novel and could be interesting for the 
researchers and stimulate further investigation.  
Nevertheless, there could be severe methodological biases, which prevent to draw a firm 
conclusion a bout the main questions of the study.  
In particular, authors should highlight how they managed the sample size of the study, since the 
number of enrolled women is extremely low. In addition, it is not clear if the authors excluded 
possible confounding fact ors (such as extremely low/high BMI, age and other variables) that 
may have influenced the main outcomes of the study.  
Authors did not declare whether the study followed the "The Strengthening the Reporting of 
Observational Studies in Epidemiology (STROBE)  statement" (PMID: 18064739), available 
through the Enhancing the QUAlity and Transparency Of health Research (EQUATOR) 
network.  
Finally, many references are really too old: there are even two references [28] and [29] of articles 
published in 1990.  
 
REQUES TED REVISIONS:  
I hereby list the most important points to address:  
- Authors appropriately stated that skin temperature patterns could be influenced by several 
elements. Did they normalize this parameter for all the other variables that are known to 
influ ence the main outcomes of the study?  
- Did authors perform any sample size before to start the enrollment? The number of 
enrolled women (n=23) is extremely low to draw firm conclusions. In addition, authors had 3 
drop-outs and 6 women with incomplete data, so the number of final analyzed women (14) is 
even lower!  
- Did authors exclude patients affected by significant comorbidities? If not, this may 
represent a significant bias.  
- Did enrolled women get any reward/payment to enter/continue the study? It would be 
mandatory to declare about this po int. 
- Did the study conform the "The Strengthening the Reporting of Observational Studies in 
Epidemiology (STROBE) statement" (PMID: 18064739), available through the Enhancing the 
QUAlity and Transparency Of health Research (EQUATOR) network? It would be mandatory to 
design this type of study following the abovementioned international standards.  
- The age of enrolled women seems extremely variable (21 -49): these extreme ages may 
have severely influenced reported outcomes.  
- The BMI of enrolled women seems extremely variable (20.3 -37.2): these extreme BMIs 
may have severely influenced reported outcomes.  
- Most of the references are too old: 2001 [8], 2002 [9], 1996 [10], 1996 [11], 2001 [12], 
2005 [13], 1998 [20], 1994 [22], 1997 [28], 1990 [29], 1990 [30]. This is completely not 
acceptable: I recommend to avoid references published more than 5 years ago.  
 
Note: This reviewer report can be downloaded - see attached pdf file.  
 
 
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.  
 
No 
 
Are the conclusions drawn adequately supported by the data shown?  
If not, please explain in your comments to the authors.  
 
No 
 
Are you able to assess any stat istics in the manus cript or would you recommend an 
additional statistical review?  
If an additional statistical review is recommended, please speci fy 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 of competing interests, considering the following questions:  
 
1. Have you in the past five years received reimbursements, f ees, funding, or salary from an 
organisation that may in any way gain or lose financial ly from the publication of this 
manuscript, either now or in the future?  
 
2. Do you hold any stocks or shares  in an organisation t hat 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 recei ved 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 competin g interests' 
below. If your reply is yes to any, please give details below.  
 
This reviewer has been recruited by a partner organization, Research Square. Reviewers with 
declared or apparent competing interests are not utilized for t hese reviews. This reviewer has 
agreed to publication of their comments online  under a Creat ive Commons A ttribution License 
attributed to Research Square and was paid a small honorarium for  completing the review within 
a specified timeframe. Honoraria for reviews such as this are paid regardless of the reviewer  
recommendation.  
 
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on my report to the authors and, if the manuscript is accepted f or publication, my named report 
including any attachments 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  
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which I do not wish to be included in my named report can be included as confidential comments 
to the editor s, which will not be published.  
 
I agree to the open peer review policy of the journal