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Racial and Ethnic Disparities in the Incidence of Severe Maternal Morbidity in the United States, 2012–2015

Admon, Lindsay K., MD, MSc; Winkelman, Tyler N. A., MD, MSc; Zivin, Kara, PhD, MS; Terplan, Mishka, MD, MPH; Mhyre, Jill M., MD; Dalton, Vanessa K., MD, MPH

doi: 10.1097/AOG.0000000000002937
Contents: Health Disparities: Original Research

OBJECTIVE: To describe racial and ethnic disparities in the incidence of severe maternal morbidity during delivery hospitalizations in the United States.

METHODS: We conducted a pooled, cross-sectional analysis of 2012–2015 data from the National Inpatient Sample to define the prevalence of chronic conditions and incidence of severe maternal morbidity among deliveries to non-Hispanic white, non-Hispanic black, Hispanic, Asian or Pacific Islander, and Native American or Alaska Native women. We used weighted multivariable logistic regression and predictive margins to generate prevalence and incidence estimates. Adjusted rate ratios and differences were calculated to quantify disparities across racial and ethnic categories. Subgroup analyses were performed to examine the incidence of severe maternal morbidity among deliveries to women with comorbid physical health conditions, behavioral health conditions, and multiple chronic conditions within each racial and ethnic category.

RESULTS: The incidence of severe maternal morbidity was significantly higher among deliveries to women in every racial and ethnic minority category compared with deliveries among non-Hispanic white women. Severe maternal morbidity occurred in 231.1 (95% CI 223.6–238.5) and 139.2 (95% CI 136.4–142.0) per 10,000 delivery hospitalizations among non-Hispanic black and non-Hispanic white women, respectively (P<.001). When excluding cases in which blood transfusion was the only indicator of severe maternal morbidity, only deliveries to non-Hispanic black women had a higher incidence of severe maternal morbidity compared with deliveries among non-Hispanic white women: 50.2 (95% CI 47.6–52.9) and 40.9 (95% CI 39.6–42.3) per 10,000 delivery hospitalizations, respectively (risk ratio 1.2 [95% CI 1.2–1.3], risk difference 9.3 [95% CI 6.5–12.2] per 10,000 delivery hospitalizations; P<.001 for each comparison). Among deliveries to women with comorbid physical and behavioral health conditions, significant differences in severe maternal morbidity were identified among racial and ethnic minority compared with non-Hispanic white women and the largest disparities were identified among women with multiple chronic conditions.

CONCLUSION: Programs for reducing racial and ethnic disparities in severe maternal morbidity may have the greatest effect focusing on women at highest risk for blood transfusion and maternity care management for women with comorbid chronic conditions, particularly multiple chronic conditions.

Racial and ethnic minority women experience a higher incidence of severe maternal morbidity, and the largest disparities exist among women with comorbid chronic conditions.

Departments of Obstetrics and Gynecology and Psychiatry, the Institute for Healthcare Policy and Innovation, and the Program on Women's Healthcare Effectiveness Research, University of Michigan, Ann Arbor, Michigan; the VA Ann Arbor Healthcare System, Ann Arbor, Michigan; the Departments of Internal Medicine and Pediatrics, Hennepin Healthcare, and Hennepin Healthcare Research Institute, Minneapolis, Minnesota; the Departments of Obstetrics and Gynecology and Psychiatry, Virginia Commonwealth University, Richmond, Virginia; and the Department of Anesthesiology, University of Arkansas, Little Rock, Arkansas.

Corresponding author: Lindsay K. Admon, MD, MSc, North Campus Research Center, 2800 Plymouth Road, Building 14, Room G100-36, Ann Arbor, MI 48109-2800; email:

Financial Disclosure Dr. Dalton received payments from the University of California San Francisco to provide content expertise during the development of a web-based educational program on early pregnancy failure. This project was funded by an anonymous donor (2012). She has received payments for expert witness work for Bayer in device litigation (2014 to the present). She received a one-time honorarium for participation on an expert advisory panel for Johnson and Johnson (2012). She is an unpaid Merck Nexplanon trainer. The other authors did not report any potential conflicts of interest.

The authors thank the Healthcare Cost and Utilization Project's data partners for their data collection efforts:

Each author has indicated that he or she has met the journal's requirements for authorship.

Peer review history is available at

Received July 02, 2018

Received in revised form August 09, 2018

Accepted August 16, 2018

© 2018 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.