Associations of multiple dimensions of socioeconomic status with adverse pregnancy outcomes

Low maternal socioeconomic status (SES) has been associated with adverse pregnancy outcomes (APOs). However, the heterogeneity of SES measures used across studies precludes a clear understanding of what exposures underlie these associations. That knowledge is essential for designing effective strategies to reduce socioeconomic disparities in perinatal health. Our objective was to examine which SES dimensions are most predictive of APOs and represent the greatest opportunity for interventions to improve perinatal health equity.

Stress, Pregnancy, and Health study participants completed psychosocial and demographic assessments during second and third trimesters. Three objective indicators of current SES were calculated based on existing approaches in the literature: a "social position" composite reflecting the household's occupational prestige and educational attainment; a "financial resources" composite that included the household's income-to-poverty ratio (IPR), wealth, and self-reported savings relative to expenses; and a composite reflecting the number of "disadvantages" the household experienced. We additionally measured three subjective markers of SES using country- and community-specific MacArthur ladders and self-reported financial strain; two measures of childhood SES, including parental education and subjective financial strain during childhood; and four measures of neighborhood SES including IPR, employment, education, and government assistance. APOs of interest included preterm birth (PTB) and hypertensive disorders of pregnancy (HDP). Log binomial models were used to estimate associations between SES measures and APOs, adjusted for race/ethnicity, marital status, and age.

Among 592 participants, 11.5% delivered preterm. Participants with lower social position had a higher risk of PTB (RR: 1.37, 95% CI: 1.02, 1.85); other objective and subjective indicators of SES were not associated with PTB risk. Multiple indicators of SES related to HDP, including current social position (RR: 1.43, 95% CI: 1.18, 1.74), financial resources (RR: 1.28, 95% CI: 1.003, 1.63), disadvantage (RR: 1.15, 95% CI: 1.04, 1.28), subjective financial strain (RR: 1.19, 95% CI: 1.03, 1.36), childhood SES (RR: 1.77, 95% CI: 1.29, 2.43), and neighborhood SES (RR: 1.43, 95% CI: 1.24, 1.67).

Social position was associated with risk for PTB and HDP. HDP was additionally associated with subjective and objective childhood SES as well as neighborhood measures of SES, suggesting that HDP may be more sensitive to SES.