title: [Associated factors related to first spermatorrhea and menarche among high and primary school students, in Chongqing].
abstract: OBJECTIVE
  To understand the status and correlative factors on menarche and first spermatorrhea among children and adolescents, in Chongqing, in order to provide theoretical basis for carrying out sex and health education in this population.
  
  
  METHODS
  By random stratified and cluster sampling, 10 498 students (5 372 boys and 5 126 girls), 5 to 18 years old and living in Chongqing urban districts, were enrolled. General situation and physical features of the population were studied. Statistics analysis system included logistic regression methods, t-test and chi-square test.
  
  
  RESULTS
  For urban kids, first experience of spermatorrhea was 0.218 years later than those living in the rural areas (Z=-73.287,P<0.001), but median age for girls in urban areas was 0.073 years earlier than in rural areas (Z=-71.589,P<0.001). Except for factor as mother's education level in the family (χ(2)=21.564, P<0.001), other family or environment related factors did not show significant difference between the two groups of boys (P>0.05). However, significant difference appeared in average family income (χ(2)=6.175,P=0.046) between two groups of girls. Data from the logistic analysis showed that BMI, hip circumference, height, weight, number of children in the family, time of sleep and the diet structure were associated with menarche. Correlative factors of boys' first spermatorrhea would include: high-energy snacks, hip circumference, weight, height, school type and mother' s education level (P<0.05).
  
  
  CONCLUSIONS
  First spermatorrhea and menstruation of boys and girls were closely related to environment of the family, diet and the time of sleep.
authors.affiliation: Research Center for Medicine and Social Development, Innovation Center for Social Risk Governance in Health, Teaching and Research Section of Maternal Care and Child and Adolescents Health, College of Public Health and Management, Chongqing Medical University, Chongqing 400016, China.
authors.forename: K Q
authors.initials: KQ
authors.lastname: Li
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: J
authors.initials: J
authors.lastname: Guo
authors.forename: B C
authors.initials: BC
authors.lastname: Yuan
authors.forename: P Y
authors.initials: PY
authors.lastname: Guan
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D002681:China; D004032:Diet; D004542:Ejaculation; D005260:Female; D006801:Humans; D008297:Male; D008572:Menarche; D012574:Schools; D012890:Sleep; D012931:Social Environment; D013334:Students / Q000706:statistics & numerical data*; D013997:Time Factors