Original Research Preterm Birth| Volume 2, ISSUE 3, 100104, August 2020

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Racial disparities in prematurity persist among women of high socioeconomic status


      Despite persistent racial disparities in preterm birth in the United States among non-Hispanic black women compared with non-Hispanic white women, it remains controversial whether sociodemographic factors can explain these differences. We sought to evaluate whether disparities in preterm birth persist among non-Hispanic black women with high socioeconomic status.

      Study Design

      We conducted a population-based cohort study of all live births in the United States from 2015 through 2017 using birth certificate data from the National Vital Statistics System. We included singleton, nonanomalous live births among women who were of high socioeconomic status (defined as having ≥16 years of education, private insurance, and not receiving Women, Infants, and Children benefits) and who identified as non-Hispanic white, non-Hispanic black, or mixed non-Hispanic black and white race. The primary outcome was preterm birth <37 weeks; secondary outcomes included preterm birth <34 and <28 weeks. In addition, analyses were repeated considering birthweight <2500 g as a surrogate for preterm birth <37 weeks, birthweight <1500 g as a surrogate for preterm birth <34 weeks, and birthweight <750 g as a surrogate for preterm birth <28 weeks’ gestation. Data were analyzed with χ2, Student t test, and logistic regression.


      A total of 2,170,686 live births met inclusion criteria, with 92.9% non-Hispanic white, 6.7% non-Hispanic black, and 0.4% both non-Hispanic white and black race. Overall, 5.9% delivered <37, 1.3% <34, and 0.3 % <28 weeks. In unadjusted analyses of women with high socioeconomic status, the preterm birth rate at each gestational age cutoff was higher for women of mixed non-Hispanic white and black race and highest for women who were non-Hispanic black only compared with women who were non-Hispanic white only. In regression models we further adjusted for women with insurance and prenatal care their entire pregnancy, maternal race was associated with higher odds of preterm birth at each gestational age cutoff, with the highest odds observed at <28 weeks. Finally, in further adjustment analysis including only the 1,934,912 women who received prenatal care in the first trimester, findings were similar. Rates of preterm birth at each gestational age cutoff remained highest for women who identified as non-Hispanic black, intermediate for women identifying as both non-Hispanic black and white race, and lowest for non-Hispanic white women at <37 weeks (9.9% vs 6.1% vs 5.5%, respectively; P < .001), <34 weeks (3.5% vs 1.5% vs 1.1%, respectively; P < .001), and <28 weeks’ gestation (1.2% vs 0.4% vs 0.2%, respectively, P < .001).


      Even among college-educated women with private insurance who are not receiving Women, Infants, and Children benefits, racial disparities in prematurity persist. These national findings are consistent with prior studies that suggest factors other than sociodemographics are important in the underlying pathogenesis of preterm birth.

      Key words

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