The impact of socioeconomic status across early life on age at menarche among a racially diverse population of girls.

PURPOSE We sought to evaluate the association between childhood socioeconomic status (SES) at two time points and age at menarche in a multiracial sample of U.S. girls. METHODS Our study population consisted of a cohort of female participants enrolled at birth at the New York site of the Collaborative Perinatal Project, who were born during the period 1959-1963 (n = 262). SES at birth, at age 7, and change between birth and age 7 were measured prospectively through an index score of family income, paternal occupation, and education. Data on age at menarche were collected retrospectively through adult self-report. We used multivariable linear regression to examine the association between SES and age at menarche after adjusting for childhood body mass index (BMI) and other covariates associated with age at menarche. RESULTS After adjustment, SES at age 7 was positively associated with age at menarche (beta: 0.015, 95% confidence interval [CI]: 0.003-0.024 per unit of SES index). Change in SES was significantly associated with age at menarche; a 20-unit decrease in SES was associated with a 4-month decrease in age at menarche. CONCLUSIONS Our results suggest that lower SES at 7 years and reductions in SES in early childhood are both associated with an earlier age at menarche.