Objectives
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.
Results
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).
Conclusion
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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Article info
Publication history
Accepted:
March 14,
2020
Received:
March 1,
2020
Footnotes
The authors report no conflict of interest.
This study was supported, in part, by the National Institute on Minority Health and Health Disparities. R01-MD011609 (to Dr Manuck).
Cite this article as: Johnson J; Green C; Vladutiu C, et al. Racial disparities in prematurity persist among women of high socioeconomic status. Am J Obstet Gynecol MFM 2020;2:100104.
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