title: National estimates of the pubertal milestones among urban and rural Chinese girls.
abstract: OBJECTIVE
  To provide clinically meaningful, normative reference data that describe pubertal timing indicators among urban and rural Chinese girls.
  
  
  METHODS
  Girls of Chinese Han ethnicity from grade 1 in elementary schools through grade 12 in junior high schools in eight regions participated in China Puberty Research Collaboration from October 2010 to May 2011. At examination, stages of breast and pubic hair development were assessed by trained physicians. Data on menses were collected through questionnaire survey.
  
  
  RESULTS
  A total of 15,388 girls aged 6.0-18.9 years participated in this collaboration study. Among them, approximately 53.5% (8,238) came from rural areas. The median ages at stage 2 of breast development of Chinese girls were 9.18 (95% confidence interval: 8.91-9.44) years and at stage 2 for pubic hair growth were 11.65 (95% confidence interval: 11.41-11.90) years. Girls with body mass index ≥85th percentile had earlier age for B2 (Tanner stage 2 for breast development), B3 (Tanner stage 3 for breast development), PH2 (Tanner stage 2 for pubic hair development), PH3 (Tanner stage 3 for pubic hair development), and menarche compared with girls with body mass index < 85th percentile. Urban girls achieved PH2, PH3, and menarche at a much earlier age than rural girls, except for B2 and B3 attainment. Mean menarcheal age is 12.43 years.
  
  
  CONCLUSIONS
  This study presented up-to-date data on female pubertal timing in a national sample of Chinese Han ethnicity girls and separately for urban and rural areas.
authors.affiliation: Department of Maternal, Child and Adolescent Health, School of Public Health, Anhui Medical University, Hefei, PR China.
authors.forename: Ying
authors.initials: Y
authors.lastname: Sun
authors.forename: Fang-Biao
authors.initials: FB
authors.lastname: Tao
authors.forename: Pu-Yu
authors.initials: PY
authors.lastname: Su
authors.forename: Jin-Cheng
authors.initials: JC
authors.lastname: Mai
authors.forename: Hui-Jing
authors.initials: HJ
authors.lastname: Shi
authors.forename: Yun-Tao
authors.initials: YT
authors.lastname: Han
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.forename: Xiao-Ming
authors.initials: XM
authors.lastname: Lou
authors.forename: Juan
authors.initials: J
authors.lastname: Han
authors.forename: Jie
authors.initials: J
authors.lastname: Liu
mesh_terms: D000293:Adolescent; D015992:Body Mass Index; D001940:Breast / Q000254:growth & development; D002648:Child; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008572:Menarche; D011627:Puberty; D012016:Reference Values; D012424:Rural Population / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires; D014505:Urban Population / Q000706:statistics & numerical data*