Reviewer ’s report  
 
Title: Factors associated with early age at menarche among Thai adolescents in Bangkok: A 
cross -sectional study  
 
Version: 0 Date: 26 Apr 2016  
 
Review er: Zeynep Atay  
 
Reviewer's report:  
 
In this cross -sectional study, the authors report the declining age at menarche and associated 
facto rs in Thai adolescents living in Bangkok. As a cross -sectional study, it is well designed in 
general. Here are some comments on the paper.  
1. As the age gets younger, the percentage of girls reaching menarche in the group gets lower. 
For example only 19.6%  of children reached menarche. So, it is possible that the average age 
at menarche in those groups with lower percentages could change as the percentage of 
children reaching menarche  increases. This makes the average age at menarche of those 
groups less r eliable. If possible, it would be a good idea if the authors turn back to the cohort  
(since 3 years elapsed from the last evaluation) and reevaluate those premenarcheal girls in 
each age group if they have menarche and if so, learn the age at menarche.  
2. In almost all groups (grouped according to year of birth), there are children whose age at 
menarche is less than 10 years. As the authors know, age at menarche <10 years would be 
called as premature menarche and those girls need to be evaluated for the presence of 
pathologies that may cause precocious puberty. So these children may need to be excluded 
from the statistical analysis. Since they probably affect the age at menarche resulting in an 
earlier age at menarche in that group. How many girls with ag e at menarche <10 years are 
present in each group.   Did the authors evaluate those children for the presence of any 
pathologies causing precocious puberty. Did the authors include these girls to the statistical 
analysis. If so, what would be the figures w hen these girls are excluded.  
3. As the authors stated, it has been known that body fat mass is among the critical factors for 
pubertal onset in girls. BMI is negatively correlated with age at breast development and 
menarche in many studies. Kaplowitz et al. demonstrated that the mean BMI Z scores for 
each age are markedly greater in 6 -9 year -old white girls with versus without breast 
development and the more advanced the breast development was the higher the BMI Z score 
was. Similar to breast development,  a positive association was reported between BMI Z score 
and likelihood of having reached menarche by Anderson et al. It would be more appropriate 
if the authors calculate and give mean± standard deviations of BMI SDS(Z scores) values 
rather than BMI. It w ould also be more accurate if they compare these BMI SDS values of 
pre and postmenarchial girls in each group separately rather than evaluating the association 
in only children with BMI>25  
 
Some minor points:  
1. Page 3, line 8: A trained research nurses? nu rse? 
2. Page 4, line 11 -15: ''The mismatch between physical development.....  should be changed into 
''Earlier age at menarche has been associated with negative behavioral....''  
3. Page 6, line 8: Daily allowance of WHAT?( Calories?)  
4. Page 6, line 15: Me thods of anthropometric mesurements( weight, height and waist 
circumference) should be described in detail.  
5. Page 10, line 22: As the authors know, leptin is secreted from white adipose tissue and acts 
on hypothalamic leptin receptors on arcuate nucleus to stimulate GnRH release. The sentence 
should be changed since it gives an impression as if leptin is secre ted from HPG system  
Are the methods appropriate and well described?  
If not, please specify what is required in your comments to the authors.  
 
Yes 
 
Does the work include the necessary controls?  
If not, please specify which contro ls 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.  
 
Yes 
 
Are you able to assess any statistics in the manuscript or would you recommen d 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 th e 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, 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, w rite '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  
 
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