Title: The Menstrual Cycle Regularity and Skin#Irregular Menstrual Cycle Affects Skin
Physiological Properties and Skin Bacterial Microbiome in Urban Chinese Women
Version: 1 Date: 13 Mar 2023
Reviewer's report:
The present study investigated the regularity of menstrual cycle-related variation in skin
physiological characteristics and skin microbiota. Although this study may provide insights into
the association between menstrual cycle regularity and skin conditions,  there are multiple issues
that must be addressed before meeting the standard for publication. The methods section was
not well written, with much key information missing.
Line 145- The authors stated that the present study was based on the investigation of the
correlation between skin health status and skin, gut microbiota of qualified volunteers living in
Shanghai. It should be "...between menstrual health status and skin...".
Line 157 - this study had no inclusion and exclusion criteria provided in the Methods section.
Some conditions such as polycystic ovary syndrome can cause irregular menstrual cycles and
may also affect the condition of the skin. The authors should consider whether PCOS patients
should be ruled out from the study.
Line 162 - Menstrual cycle regularity was self-reported from the following question: “Do you
have a regular menstrual cycle?” Did the researchers explain what is a regular menstrual cycle
to the participants? Do the authors have an objective criterion for evaluating irregular menstrual
cycles? The menstrual cycle regularity should not be evaluated based on one simple question.
Line 164 - Menstrual cycle regularity was classified into three categories: regular, less regular,
and irregular. What is the definition of regular, less regular, and irregular?
Table 1 - the authors provided general characteristics of the participants in Table 1. The authors
should compare whether there are differences in each characteristic between the three groups,
for example, whether there was a difference in age between the three groups. The authors also
mentioned, after all, that age can affect skin condition.  In addition, can the authors explain the
definition of "different stages of menstrual cycle"?
Social-demographic information was also missing in the present study. There are multiple social-
demographic characteristics that would affect both menstrual regularity and skin condition. For
example, did the authors consider the effect of BMI when conducting their research? These
characteristics may have a confounding effect on the results of the study.
Line 171 - All subjects were required not to use skin care products and cosmetics after washing
their faces the night before the measurement and the day of the test. Can the effect of skin care
products on the experiment results be ruled out by stopping the use of skin care products for
only less than 1 day?
Line 234 -  most of women suffered from less regular menstrual cycles. The authors must clarify
the definition of " less regular menstrual cycles"
The authors should provide their  Self-Evaluation Questionnaire in the supplementary materials.
Finally, the manuscript needs thorough English language editing before meeting the standard
for publication.