Reviewer ’s report  
 
Title: Nocturnal finger skin temperature in menstrual cycle trackin g: Ambulatory pilot study 
using a wearable Oura ring  
 
Version: 0 Date: 29 Apr 2019  
 
Reviewer: Victoria H. Jennings  
 
Reviewer's report:  
This manuscript will require extensive editing for an English -speaking audience.   
 
I have severa l comments that should be addressed.  Throughout the authors refer to "detecting" 
[the first day of] menses.  From the context, it appears they mean "predicting" rather than 
"detecting".  Please clarify.  
This is a very small sample size with missing data ( missing temperature measurements) and early 
exit.  This is mentioned in the discussion under shortcomings of the study, but it should also be 
acknowledged earlier in the study -- perhaps in the section explaining the study design.  Why 
would we think that a data set this small would so anything other than give us an idea about 
whether the authors are on the right track and should design a larger study?  
Please provide more information on One Step Ovulation Testing Midstream.  Note also that it 
measures urina ry LH and apparently uses its rise as a proxy for ovulation.  This needs to be 
justified.   
The definition of the Calendar approach is faulty.  I am unaware of any similar definition in the 
literature.  See instead:  Hatcher et al, Contraceptive Technology , 21st edition: Chapter 12, 
Fertility Awareness -Based Methods, p. 408.  In addition, given the sample size and lack of 
controls, I recommend that the authors eliminate any comparison with a Calendar approach.  It 
does not strengthen the paper.  
 
Also note another recent paper: Handel and Wahlstrom, Digital contraceptives based on basal 
body temperature measurements. Biomedical Signal Processing and Control, Volume 52,, July 
2019, pages 141 -151.  It is relevant to this paper.   
 
 
 
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
Unable to assess  
 
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 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 recommend additi onal statistical review  
 
Quality of written English  
Please indicate the quality of language in the manuscript:  
 
Not suitable for publication unless extensively edited  
 
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.  
 
I am involved in studies of other approaches to determining the fertile window of the menstrual 
cycle, including the Standard Days Method and Dot (Dynamic  Optimal Timing). None of these 
involve BBT measure ments however. I receive grants from the U.S. government and foundations  
for conducting these studies. Otherwise, I declare that I have no competing interests.  
 
I agree to the open peer review policy of the journal. I understan d that my name will be included 
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  
CC-BY license ( http://creativecommons.org/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 editor s, which will not be published.  
 
I agree to the open peer review policy of the journal