Table 1. Principal clinical characteristics of subjects according to menstrual irregularity in Korean National Health and Nutrition Examination Survey 2010-2012.

Values are presented as mean±standard error (SE) or % (SE).

^*Obtained by chi-square or Student t-tests. ^†Physical activity was defined using the International Physical Activity Questionnaire. The regular exercise group included subjects who exercised moderately more than five times a week for 30 minutes per session or those who exercised intensively more than three times a week for 20 minutes per session. ^‡Household income was adjusted for the number of family members; the household income was divided into quartiles. 'Low income' and 'low education' were defined as the lowest quartile of income and ≤9 years of education, respectively. ^§Triglycerides levels were logarithmic transformed because of their skewed distribution.