Purpose: 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.
Keywords: Cohort study; Ethnic groups; Menarche; Socioeconomic factors.
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