Abstract: Objective：To analyze the current situation of age at menarche (AAM) in Chinese ethnic minority girls aged 9-18 years, and compare the AAM with that of Chinese Han girls from the same province or autonomous region. Methods: Probit analyses were used to calculate the AAM in various ethnic minority groups of Chinese girls who participated in 2010 National Physical Fitness and Health Surveillance. The sample size of ethnic minority girls was 31 711, and the ethnic minorities were Mongolian, Hui, Tibetan, Uighur, Miao, Yi, Zhuang, Buyi, Korean, Dong, Yao, Bai, Tujia, Hani, Kazak, Dai, Li, Lisu, Wa, Shui, Dongxiang, Naxi, Kirgiz, Tu, Qiang and Sala. The local Han girls to compare with the AAM were also surveyed in 2010 National Physical Fitness and Health Surveillance. Results: In the 13-year-old group, the percentage of menarche in Sala was the lowest (32.17%), while that in Korean was the highest (93.23%). At the age of 18, 99.60% ethnic minority girls appeared menstruating. The AAM of the top 3 ethnic minority groups were Korean (11.79 years), Mongolian (12.44 years) and Zhuang (12.52 years); and the last 3 ethnic minority groups were Dongxiang (14.36 years), Sala (14.32 years) and Shui (14.02 years). The AAM in Korean was 0.93 years earlier than that of the Han girls from Jilin province; the AAM in Mongolian was 0.14 years earlier than that of the Han girls from Neimenggu autonomous region; the AAM in Naxi and Qiang was close to that of the Han girls in the same province (region) (P>0.05); and the AAM in Hui, Uighur, Miao, Yi, Zhuang, Buyi, Dong, Yao, Bai, Tujia, Hani, Kazak, Dai, Li, Lisu, Wa, Shui, Dongxiang, Kirgiz, Tu, and Sala was later than that of the Han girls in the same province (region). The cluster analysis indicated that the 26 ethnic minority groups could be classified as three groups: Korean were classified into the earlier age group of AAM; Dongxiang, Sala, Uighur, Yi and Shui belonged to the later age group of AAM; and the other 20 ethnic minority groups were into the middle age group of AAM. Conclusion: There was a large variation among different ethnic minority groups in China. The AAM was earlier in Korean, and Mongolian, compared with the local Han girls, and the AAM in other ethnic minority groups was the same or later compared with the local Han girls.

Key words: Menarche, Adolescent development, Minority groups, Students