title: Timing of reproductive maturation in rural versus urban Tonga boys, Zambia.
abstract: BACKGROUND
  Population variation in the timing of reproductive maturation among boys has received relatively little attention. However, evidence that the timing of pubertal onset is related to measures of adiposity suggests that the onset of reproductive maturation among boys in populations with poor nutritional status will be delayed.
  
  
  OBJECTIVE
  This study seeks to determine the impact of nutritional status on the timing of reproductive maturation by comparing urban and rural boys in an African population.
  
  
  METHODS
  Subjects were 794 rural and urban Tonga boys from Zambia, ages 5-19. Onset of puberty was defined as testicular volume >3 mL, which was measured using Prader beads. Data on height, weight, triceps skinfolds, and dental development were also obtained.
  
  
  RESULTS
  Onset of testicular growth was 11.2 years (95% CI 10.9-11.4) for urban boys and 12.4 (95% CI 12.1-12.9) years for rural boys. Completion of testicular growth was also earlier in the urban sample: 15.3 years (95% CI 15.0-5.6) versus 17.1 years (95% CI 15.6-25.2). Both onset and completion of testicular growth were significantly and positively related to height and arm muscle area. In addition, triceps skinfolds by residence interaction was a significant predictor of testicular maturity, indicating a stronger relationship between energetic status and testicular growth in the rural sample.
  
  
  CONCLUSIONS
  Our results demonstrate that delayed onset and slow testicular development among rural Gwembe boys is related to poor nutritional status.
authors.affiliation: Department of Anthropology, Boston University, MA 02215, USA. bcampbel@bu.edu
authors.forename: B C
authors.initials: BC
authors.lastname: Campbell
authors.forename: R
authors.initials: R
authors.lastname: Gillett-Netting
authors.forename: M
authors.initials: M
authors.lastname: Meloy
mesh_terms: D000293:Adolescent; D000328:Adult; D001823:Body Composition / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D006801:Humans; D008297:Male; D009752:Nutritional Status; D012424:Rural Population; D012741:Sexual Maturation / Q000502:physiology*; D014505:Urban Population; D015024:Zambia