Black-White Disparities in Preterm Birth: Geographic, Social, and Health Determinants.

Introduction: Reducing racial/ethnic disparities in preterm birth is a priority for U.S. public health programs. The study objective was to quantify the relative contribution of geographic, sociodemographic, and health determinants to the black, non-Hispanic and white, non-Hispanic preterm birth disparity.

Methods: Cross-sectional 2016 U.S. birth certificate data (analyzed in 2018-2019) were used. Black-white differences in covariate distributions and preterm birth and very preterm birth rates were examined. Decomposition methods for nonlinear outcomes based on logistic regression were used to quantify the extent to which black-white differences in covariates contributed to preterm birth and very preterm birth disparities.

Results: Covariate differences between black and white women were found within each category of geographic, sociodemographic, and health characteristics. However, not all covariates contributed substantially to the disparity. Close to 38% of the preterm birth and 31% of the very preterm birth disparity could be explained by black-white covariate differences. The largest contributors to the disparity included maternal education (preterm birth, 11.3%; very preterm birth, 9.0%), marital status/paternity acknowledgment (preterm birth, 13.8%; very preterm birth, 14.7%), source of payment for delivery (preterm birth, 6.2%; very preterm birth, 3.2%), and hypertension in pregnancy (preterm birth, 9.9%; very preterm birth, 8.3%). Interpregnancy interval contributed a more sizable contribution to the disparity (preterm birth, 6.2%, very preterm birth, 6.0%) in sensitivity analyses restricted to all nonfirstborn births.

Conclusions: These findings demonstrate that the known portion of the disparity in preterm birth is driven by sociodemographic and preconception/prenatal health factors. Public health programs to enhance social support and preconception care, specifically focused on hypertension, may provide an efficient approach for reducing the racial gap in preterm birth.