Socioeconomic disadvantage and racial/ethnic disparities in low-risk cesarean birth in California.

Our objective was to assess the relationship of socioeconomic disadvantage and race/ethnicity with low-risk cesarean birth. We examined birth certificates (2007-2018) linked with maternal hospitalization data from California; the outcome was cesarean birth among low-risk deliveries (ie, nulliparous, term, singleton, vertex [NTSV]). We used generalized estimation equation Poisson regression with an interaction term for race/ethnicity (n = 7 groups) and a measure of socioeconomic disadvantage (census tract-level neighborhood deprivation index, education, or insurance). Among 1 815 933 NTSV births, 26.6% were by cesarean section. When assessing the joint effect of race/ethnicity and socioeconomic disadvantage among low-risk births, risk of cesarean birth increased with socioeconomic disadvantage for most racial/ethnic groups, and disadvantaged Black individuals had the highest risks. For example, Black individuals with a high school education or less had a risk ratio of 1.49 (95% CI, 1.45-1.53) relative to White individuals with a college degree. The disparity in risk of cesarean birth between Black and White individuals was observed across all strata of socioeconomic disadvantage. Asian American and Hispanic individuals had higher risks than White individuals at lower socioeconomic disadvantage; this disparity was not observed at higher levels of disadvantage. Black individuals have a persistent, elevated risk of cesarean birth relative to White individuals, regardless of socioeconomic disadvantage.