title: National estimates of the timing of sexual maturation and racial differences among US children.
abstract: OBJECTIVE
  To provide clinically meaningful, normative reference data that describe the timing of sexual maturity indicators among a national sample of US children and to determine the degree of racial/ethnic differences in these estimates for each maturity indicator.
  
  
  METHODS
  Tanner staging assessment of sexual maturity indicators was recorded from 4263 non-Hispanic white, black, and Mexican American girls and boys aged 8.00 to 19.00 years as part of the Third National Health and Nutrition Examination Survey (NHANES III) conducted between 1988 and 1994. NHANES III followed a complex, stratified, multistage probability cluster design. SUDAAN was used to calculate the mean age and standard error for each maturity stage and the proportion of entry into a maturity stage and to incorporate the sampling weight and design effects of the NHANES III complex sampling design. Probit analysis and median age at entry into a maturity stage and its fiducial limits were calculated using SAS 8.2.
  
  
  RESULTS
  Reference data for age at entry for maturity stages are presented in tabular and graphical format. Non-Hispanic black girls had an earlier sexual development for pubic hair and breast development either by median age at entry for a stage or for the mean age for a stage than Mexican American or non-Hispanic white girls. There were few to no significant differences between the Mexican American and non-Hispanic white girls. Non-Hispanic black boys also had earlier median and mean ages for sexual maturity stages than the non-Hispanic white and Mexican American boys.
  
  
  CONCLUSIONS
  Non-Hispanic black girls and boys mature early, but US children completed their sexual development at approximately the same ages. The present reference data for the timing of sexual maturation are recommended for the interpretation of assessments of sexual maturity in US children.
authors.affiliation: The Lifespan Health Research Center Departments of Community Health, Pediatrics, and Mathematics and Statistics, Wright State University, School of Medicine, Dayton, Ohio 45420, USA. shumei.sun@wright.edu
authors.forename: Shumei S
authors.initials: SS
authors.lastname: Sun
authors.forename: Christine M
authors.initials: CM
authors.lastname: Schubert
authors.forename: William Cameron
authors.initials: WC
authors.lastname: Chumlea
authors.forename: Alex F
authors.initials: AF
authors.lastname: Roche
authors.forename: Howard E
authors.initials: HE
authors.lastname: Kulin
authors.forename: Peter A
authors.initials: PA
authors.lastname: Lee
authors.forename: John H
authors.initials: JH
authors.lastname: Himes
authors.forename: Alan S
authors.initials: AS
authors.lastname: Ryan
mesh_terms: D000293:Adolescent; D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data; D000367:Age Factors; D044383:Black People; D015992:Body Mass Index; D002648:Child; D005260:Female; D006128:Growth / Q000502:physiology; D006306:Health Surveys; D006801:Humans; D008297:Male; D017058:Mexican Americans / Q000706:statistics & numerical data; D009749:Nutrition Surveys; D011627:Puberty / Q000502:physiology*; D044469:Racial Groups; D012016:Reference Values; D012727:Sex Characteristics; D012741:Sexual Maturation / Q000502:physiology*; D014481:United States; D044465:White People