Black-White Preterm Birth Disparity: A Marker of Inequality

Purpose: The racial disparity in preterm birth (PTB) is a persistent feature of perinatal epidemiology. Its consistency is not only an outcome of reproductive interest but may function as a persistent inequality to which women are exposed over time. Herein we sought to analyze exposure to area-level PTB disparity and its association with individual-level PTB risk. Methods: Using geocoded birth records (1999-2001) and year 2000 census data for Wake County, North Carolina, we created a tract-level PTB disparity variable for each woman in our study area, comprising all births in her tract excluding her birth. Multilevel random intercept models for exposure to neighborhood PTB disparity and odds of PTB were fit. Results: Exposure to area-level PTB disparity was associated with increased odds of PTB for all women. After adjustment for maternal and neighborhood covariates, odds of delivering preterm increased by 25%, 26%, and 36% for the second, third, and fourth quartiles of exposure to PTB disparity (odds ratio [OR] = 1.25, 95% confidence interval [CI]: 1.00-1.57; OR = 1.26, 95% CI: 1.01-1.58; and OR = 1.36, 95% CI: 1.06-1.75, respectively). Conclusions: Exposure to persistent inequality, in the form of PTB disparity, appears associated with individual-level PTB risk. Knowing where PTB disparity is greatest has implications for PTB prevention policy efforts to buffer adverse conditions.