title: Critical period for menarche derived by the wavelet interpolation method from changes in BMI with age in South Korean girls.
abstract: Recently, few studies regarding the changes in BMI with age have been reported. In the present study, the wavelet interpolation method (WIM) was applied to the changes in BMI with age from the first grade of elementary school until the second year of high school in Korean girls, and the relationship between age at the maximum peak velocity (MPV) of BMI and age at menarche was confirmed by determining the age at MPV of BMI. Age at menarche and activity status were obtained from questionnaires given to 263 second grade high school girls in the Pusan area of South Korea. Moreover, longitudinal growth data on height and weight from the first grade of elementary school until the second year of high school (from 1997 to 2008) were obtained from health examination records. BMI was calculated from height and weight values from the first grade of elementary school until the second year of high school, and wavelet interpolation was applied to the distances of BMI in each grade. The change curve of BMI with age was determined by wavelet interpolation, and the age at MPV of BMI was determined from the changes in the velocity curve with age as the differentiation curve. Age at MPV of BMI was found to be 12.76 +/- 1.6 years, and age at menarche to be 12.34 +/- 1.1 years. The interval in age at the two times was -0.42 +/- 1.6 years, and a significant difference was seen between age at menarche and age at MPV of BMI. The reason that the age at menarche was a little earlier than the age at MPV of BMI is hypothesized to be abnormal melatonin levels influenced by lack of sleep in Korean school girls. However, it is proposed that the age at MPV of BMI is valid as the critical period for the age at menarche.
authors.affiliation: Graduate School of Business Administration and Computer Science, Aichi Institute of Technology, 1247, Yachigusa, Yakusa-chou, Toyota, Aichi 470-0392, Japan. fujii@aitech.ac.jp
authors.forename: Katsunori
authors.initials: K
authors.lastname: Fujii
authors.forename: Nozomi
authors.initials: N
authors.lastname: Tanaka
mesh_terms: D000293:Adolescent; D000367:Age Factors; D015992:Body Mass Index; D002648:Child; D005260:Female; D006801:Humans; D008572:Menarche; D056910:Republic of Korea