Division of Maternal-Fetal Medicine, Department of Obstetrics & Gynecology, University of North Carolina, Chapel Hill, NC.
Am J Obstet Gynecol MFM. 2020 Aug;2(3):100104. doi: 10.1016/j.ajogmf.2020.100104. Epub 2020 Mar 23.
Despite persistent racial disparities in preterm birth (PTB) in the US among non-Hispanic (NH) black women compared to NH white women, it remains controversial whether sociodemographic factors can explain these differences. We sought to evaluate whether disparities in PTB persist among NH black women with high socioeconomic status (SES).
We conducted a population-based cohort study of all live births in the US from 2015-2017 using birth certificate data from the National Vital Statistics System. We included singleton, non-anomalous live births among women who were of high SES (defined as having ≥ 16 years of education, private insurance, and not receiving Women, Infants and Children [WIC] benefits) and who identified as NH white, NH black, or 'mixed' NH black and white race. The primary outcome was PTB <37 weeks; secondary outcomes included PTB <34 and <28 weeks. In addition, analyses were repeated considering birthweight <2500g as a surrogate for preterm birth <37 weeks, birthweight <1500g as a surrogate for preterm birth <34 weeks, and birthweight <750g as a surrogate for preterm birth <28 weeks' gestation. Data were analyzed with chi-square, t-test, and logistic regression.
2,170,686 live births met inclusion criteria, with 92.9% NH white, 6.7% NH black, and 0.4% both NH white and black race. Overall, 5.9% delivered <37, 1.3% <34, and 0.3 % <28 weeks. In unadjusted analyses of women with high SES, the PTB rate at each gestational age cutoff was higher for women of 'mixed' NH white and black race, and highest for women who were NH black only compared to women who were NH 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 PTB at each GA cutoff, with the highest odds observed at <28 weeks. Finally, in further adjustement 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<0.001), <34 weeks (3.5% vs. 1.5% vs. 1.1%, respectively; p<0.001), and <28 weeks' gestation (1.2% vs. 0.4% vs. 0.2%, respectively, p<0.001).
Even among college-educated women with private insurance who are not receiving WIC, racial disparities in prematurity persist. These national findings are consistent with prior studies that suggest factors other than socio-demographics are important in the underlying pathogenesis of PTB.
尽管在美国，非西班牙裔（NH）黑人女性与 NH 白人女性相比，早产（PTB）的种族差异持续存在，但社会人口因素是否能解释这些差异仍存在争议。我们旨在评估 NH 黑人中具有较高社会经济地位（SES）的女性中，PTB 是否存在差异。
我们使用国家生命统计系统的出生证明数据，对 2015-2017 年美国所有活产儿进行了基于人群的队列研究。我们纳入了 SES 较高（定义为≥16 年教育、私人保险和不接受妇女、婴儿和儿童[WIC]福利）且 NH 白人、NH 黑人或 NH 黑白混合种族的单胎、非异常活产儿。主要结局是 PTB<37 周；次要结局包括 PTB<34 周和<28 周。此外，还考虑了将出生体重<2500g 作为早产<37 周的替代指标、出生体重<1500g 作为早产<34 周的替代指标、以及出生体重<750g 作为早产<28 周妊娠的替代指标，重复了分析。数据采用卡方检验、t 检验和逻辑回归进行分析。
2170686 例活产符合纳入标准，其中 92.9%为 NH 白人，6.7%为 NH 黑人，0.4%为 NH 黑白混合种族。总体而言，5.9%的婴儿在<37 周分娩，1.3%的婴儿在<34 周分娩，0.3%的婴儿在<28 周分娩。在 SES 较高的女性中进行的未调整分析中，在每个妊娠年龄截止点，NH 黑白混合种族的女性 PTB 率更高，而仅 NH 黑人的女性比仅 NH 白人的女性更高。在我们进一步调整了有保险和整个孕期产前护理的女性的回归模型中，产妇种族与每个 GA 截止点的 PTB 几率相关，在<28 周时观察到的几率最高。最后，在包括仅接受了第一次妊娠产前护理的 1934912 名女性的进一步调整分析中，发现结果相似。在<37 周（9.9%比 6.1%比 5.5%，分别；p<0.001）、<34 周（3.5%比 1.5%比 1.1%，分别；p<0.001）和<28 周的妊娠（1.2%比 0.4%比 0.2%，分别；p<0.001）的每个妊娠年龄截止点，非西班牙裔黑人女性的早产率仍然最高。
即使在接受私人保险且未接受 WIC 的受过大学教育的女性中，早产的种族差异仍然存在。这些全国性发现与之前的研究一致，表明除社会人口因素外，其他因素在早产的潜在发病机制中很重要。
