Decomposing Black-White and Hispanic-White Disparities in Infant Prematurity by Maternal Age and Maternal Educational Attainment in the U.S., 2004-2023.

Black-white infant prematurity gaps have been persistently large, and, in comparison, Hispanic-white gaps have been persistently small over time, demonstrating a Hispanic prematurity paradox. However, the consistency of prematurity gaps may be masking heterogeneity in the predictors of these gaps over time. In recent decades the United States has experienced large increases in maternal age and maternal educational attainment, two underlying demographic predictors of prematurity. Yet, whether and how changes in racialized patterns of maternal age and maternal educational attainment have influenced racialized prematurity gaps is unclear. Using U.S. National Vital Statistics data from 2004 to 2023, I use the Kitagawa-Oaxaca-Blinder approach to decompose Black-white and Hispanic-white gaps in prematurity into the portions explained by differences in endowments and differences in coefficients of maternal age and maternal educational attainment. Of note, results show that maternal age-related weathering, as measured by differences in coefficients on maternal age, explains almost none (< 1%) of the Black-white or Hispanic-white prematurity gaps. Rather, differences in maternal education composition explain large, but shrinking portions of the Hispanic-white prematurity gap (161% in 2004–2005 and 91% in 2022–2023) and an important and growing portion of the Black-white prematurity gap over time (12% in 2004–2005 and 18% in 2022–2023). Unmeasured factors explain the bulk of the Black-white prematurity gap in both periods (85–90%) and a growing portion Hispanic-white gap, going from reducing the gap in 2004–2005 (-41%) to explaining a large portion of the gap in 2022–2023 (32%). Future investigations into unmeasured factors may lead to new insights into the drivers of prematurity gaps as well as the Hispanic prematurity paradox.