title: Socioeconomic status and age at menarche: an examination of multiple indicators in an ethnically diverse cohort.
abstract: OBJECTIVE
  Ethnic disparities exist in US girls' ages at menarche. Overweight and low socioeconomic status (SES) may contribute to these disparities but past research has been equivocal. We sought to determine which SES indicators were associated uniquely with menarche, for which ethnic groups, and whether associations operated through overweight.
  
  
  METHODS
  Using National Longitudinal Study of Youth data, we examined associations between SES indicators and age at menarche. Participants were 4851 girls and their mothers. We used survival analyses to examine whether SES, at various time points, was associated with menarche, whether body mass index mediated associations, and whether race/ethnicity modified associations.
  
  
  RESULTS
  Black and Hispanic girls experienced menarche earlier than whites. After adjusting for SES, there was a 50% reduction in the effect estimate for "being Hispanic" and 40% reduction for "being black" versus "being white" on menarche. SES indicators were associated uniquely with earlier menarche, including mother's unmarried status and lower family income. Associations varied by race/ethnicity. Body mass index did not mediate associations.
  
  
  CONCLUSIONS
  Racial differences in menarche may in large part be due to SES differences. Future experimental or quasiexperimental studies should examine whether intervening on SES factors could have benefits for delaying menarche among blacks and Hispanics.
authors.affiliation: Community Health and Human Development Division, School of Public Health, University of California, Berkeley. Electronic address: jdeardorff@berkeley.edu.
authors.forename: Julianna
authors.initials: J
authors.lastname: Deardorff
authors.affiliation: Epidemiology Division, School of Public Health, University of California, Berkeley.
authors.forename: Barbara
authors.initials: B
authors.lastname: Abrams
authors.affiliation: Epidemiology Division, School of Public Health, University of California, Berkeley.
authors.forename: John Paul
authors.initials: JP
authors.lastname: Ekwaru
authors.affiliation: School of Medicine, Stanford University, Stanford, CA.
authors.forename: David H
authors.initials: DH
authors.lastname: Rehkopf
mesh_terms: D000293:Adolescent; D001741:Black or African American / Q000706:statistics & numerical data; D017677:Age Distribution; D015992:Body Mass Index; D005006:Ethnicity / Q000706:statistics & numerical data*; D005260:Female; D006630:Hispanic or Latino / Q000706:statistics & numerical data; D006801:Humans; D008137:Longitudinal Studies; D008572:Menarche / Q000208:ethnology*; D009035:Mothers / Q000706:statistics & numerical data*; D050177:Overweight / Q000208:ethnology*; D012923:Social Class; D044465:White People / Q000706:statistics & numerical data
keywords: Cohort study; Ethnic groups; Menarche; Socioeconomic factors
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