black-white differences in the association between maternal age at childbirth and income

Background: previous research has documented bidirectional associations between age at childbirth and socioeconomic status (ses) among mothers. built on the marginalization-related diminished returns (mdrs) theory, this study compares the association between maternal age at childbirth and income between non-hispanic blacks and non-hispanic whites. methods: we used the data of the fragile families and child well-being study (ffcws), a longitudinal study from 1998 to 2016 in the united states (us). this study included 2922 women who were non-hispanic white (n=776) or non-hispanic black (n=2146). maternal age at childbirth was the independent variable, and income was the dependent variable. educational attainment, marital status, delivery characteristics, car ownership, and welfare dependence were the covariates. for data analysis, linear regressions were applied. results: higher maternal age at childbirth was associated with higher income (adjusted b=0.30). we found a significant interaction between maternal age at childbirth and race on income, suggesting that the positive association between mothers’ age at childbirth and income was weaker for non-hispanic blacks than non-hispanic whites (b=-1.14, 95% ci=-1.50, -0.77). conclusion: postponing childbirth may have a smaller economic return for non-hispanic black women, which is in line with marginalization-related diminished returns theory. diminished returns of postponing reproduction may be a result of social stratification and structural inequalities that separate the lived experience of blacks and whites in the united states.