The Association of Race and Ethnicity with Severe Maternal Morbidity among Individuals Diagnosed with Hypertensive Disorders of Pregnancy
Authors: Palatnik Anna , McGee Paula , Bailit Jennifer L. , Wapner Ronald J. , Varner Michael W. , Thorp John M. , Caritis Steve N. , Prasad Mona , Tita Alan T. N. , Saade George R. , Rouse Dwight J. , Blackwell Sean C. ,   for the Eunice Kennedy Shriver National Institute of Child Health Human Development Maternal-Fetal Medicine Units (MFMU) Network
Published: June 2022

Objective This study aimed to examine whether there are racial disparities in severe maternal morbidity (SMM) in patients with hypertensive disorders of pregnancy (HDP).
Study Design Secondary analysis of an observational study of 115,502 patients who had a live birth at ≥20 weeks in 25 hospitals in the United States from 2008 to 2011. Only patients with HDP were included in this analysis. Race and ethnicity were categorized as non-Hispanic White, non-Hispanic Black (NHB), and Hispanic and were abstracted from the medical charts. Patients of other races and ethnicities were excluded. Associations were estimated between race and ethnicity, and the primary outcome of SMM, defined as any of the following, was estimated by unadjusted logistic and multivariable backward logistic regressions: blood transfusion ≥4 units, unexpected surgical procedure, need for a ventilator ≥12 hours, intensive care unit (ICU) admission, or failure of ≥1 organ system. Multivariable models were run classifying HDP into three levels as follows: (1) gestational hypertension; (2) preeclampsia (mild, severe, or superimposed); and (3) eclampsia or HELLP (hemolysis, elevated liver enzymes, and low platelet count) syndrome.
Results A total of 9,612 individuals with HDP met inclusion criteria. No maternal deaths occurred in this cohort. In univariable analysis, non-Hispanic White patients were more likely to present with gestational hypertension whereas NHB and Hispanic patients were more likely to present with preeclampsia. The frequency of the primary outcome, composite SMM, was higher in NHB patients compared with that in non-Hispanic White or Hispanic patients (11.8 vs. 4.5% in non-Hispanic White and 4.8% in Hispanic, p < 0.001). This difference was driven by a higher frequency of blood transfusions and ICU admissions among NHB individuals. Prior to adjusting the analysis for confounding factors, the odds ratio (OR) of primary composite outcomes in NHB individuals was 2.85 (95% confidence interval [CI]: 2.38, 3.42) compared with non-Hispanic White. After adjusting for sociodemographic and clinical factors, hospital site, and the severity of HDP, the OR of composite SMM did not differ between the groups (adjusted OR [aOR] = 1.26, 95% CI: 0.95, 1.67 for NHB, and aOR = 1.29, 95% CI: 0.94, 1.77 for Hispanic, compared with non-Hispanic White patients). Sensitivity analysis was done to exclude one single site that was an outliner with the highest ICU admissions and demonstrated no difference in ICU admission by maternal race and ethnicity.
Conclusion NHB patients with HDP had higher rates of the composite SMM compared with non-Hispanic White patients, driven mainly by a higher frequency of blood transfusions and ICU admissions. However, once severity and other confounding factors were taken into account, the differences did not persist.
Key Points