Measuring socioeconomic status/position in studies of racial/ethnic disparities: Maternal and infant health

Objective. Theoretical and empiric considerations raise concerns about how socioeconomic status/position (abbreviated here as SES) is often measured in health research. The authors aimed to guide the use of two common socioeconomic indicators, education and income, in studies of racial/ethnic disparities in low birthweight, delayed prenatal care, unintended pregnancy, and breastfeeding intention. Methods. Data from a statewide postpartum survey in California (N = 10,055) were linked to birth certificates. Overall and by race/ethnicity, the authors examined: (a) correlations among several measures of education and income; (b) associations between each SES measure and health indicator; and (c) racial/ethnic disparities in the health indicators "adjusting" for different SES measures. Results. Education-income correlations were moderate and varied by race/ethnicity. Racial/ethnic associations with the health indicators varied by SES measure, how SES was specified, and by health indicator. Conclusions. Conclusions about the role of race/ethnicity could vary with how SES is measured. Education is not an acceptable proxy for income in studies of ethnically diverse populations of childbearing women. SES measures generally should be outcome- and population-specific, and chosen on explicit conceptual grounds; researchers should test multiple theoretically appropriate measures and consider how conclusions might vary with how SES is measured. Researchers should recognize the difficulty of measuring SES and interpret findings accordingly.