title: [Relevant factors of early puberty timing in urban primary schools in Chongqing].
abstract: OBJECTIVE
  To investigate the status of puberty timing and relevant factors of early puberty timing in children from grade one to four in urban primary schools of Chongqing.
  
  
  METHODS
  According to the purposive sample method, four urban primary schools in Chongqing were selected and of which 1471 children from grade one to four who have obtained informed consent were recruited. Questionnaire survey on social-demographic characteristics and family environment (e.g., age, parents' relationship, diet and lifestyle, etc), and Pubertal Development Scale (PDS) survey and physical examination (measurements of height, weight, pubertal development status, etc) were conducted. P25, P50, P75 ages of each important pubertal event were calculated by probit regression. Univariate and multivariate analysis were used to analyze relevant factors.
  
  
  RESULTS
  The detection rate of early puberty timing was 17.7%, and the median ages of the onset of breast and testicular development were 10.77 and 11.48 years old, respectively. Multivariate logistic regression showed that early puberty timing occurred more likely in girls than in boys (OR = 0.561, 95% CI 0.406-0.774), and bad relationship between parents (OR = 1.320, 95% CI 1.007-1.729) and hair-products-use (OR = 1.685, 95%, CI 1.028-2.762) were risk factors of early puberty timing.
  
  
  CONCLUSIONS
  Early onset of puberty in urban Chongqing is still exist. Gender, parents' relationship, and hair-products-use have an essential impact on early puberty timing.
authors.forename: Yan
authors.initials: Y
authors.lastname: Luo
authors.forename: Qin
authors.initials: Q
authors.lastname: Liu
authors.forename: Yi
authors.initials: Y
authors.lastname: Wen
authors.forename: Shudan
authors.initials: S
authors.lastname: Liu
authors.forename: Xun
authors.initials: X
authors.lastname: Lei
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
mesh_terms: D001835:Body Weight; D002648:Child; D005260:Female; D006203:Hair Preparations; D006801:Humans; D016015:Logistic Models; D008297:Male; D010287:Parent-Child Relations; D011627:Puberty; D011629:Puberty, Precocious; D012307:Risk Factors; D012574:Schools; D011795:Surveys and Questionnaires; D014505:Urban Population
chemical_list: D006203:Hair Preparations