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Frequency of and Factors Associated With Severe Maternal Morbidity

Grobman, William A. MD, MBA; Bailit, Jennifer L. MD, MPH; Rice, Madeline Murguia PhD; Wapner, Ronald J. MD; Reddy, Uma M. MD, MPH; Varner, Michael W. MD; Thorp, John M. Jr MD; Leveno, Kenneth J. MD; Caritis, Steve N. MD; Iams, Jay D. MD; Tita, Alan T. MD, PhD; Saade, George MD; Sorokin, Yoram MD; Rouse, Dwight J. MD; Blackwell, Sean C. MD; Tolosa, Jorge E. MD, MSCE; Van Dorsten, J. Peter MD

doi: 10.1097/AOG.0000000000000173
Contents: Original Research

OBJECTIVE: To estimate the frequency of severe maternal morbidity, assess its underlying etiologies, and develop a scoring system to predict its occurrence.

Supplemental Digital Content is Available in the Text.

METHODS: This was a secondary analysis of a Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network cohort of 115,502 women and their neonates born in 25 hospitals across the United States over a 3-year period. Women were classified as having severe maternal morbidity according to a scoring system that takes into account the occurrence of red blood cell transfusion (more than three units), intubation, unanticipated surgical intervention, organ failure, and intensive care unit admission. The frequency of severe maternal morbidity was calculated and the underlying etiologies determined. Multivariable analysis identified patient factors present on admission that were independently associated with severe maternal morbidity; these were used to develop a prediction model for severe maternal morbidity.

RESULTS: Among 115,502 women who delivered during the study period, 332 (2.9/1,000 births, 95% confidence interval 2.6–3.2) experienced severe maternal morbidity. Postpartum hemorrhage was responsible for approximately half of severe maternal morbidity. Multiple patient factors were found to be independently associated with severe maternal morbidity and were used to develop a predictive model with an area under the receiver operating characteristic curve of 0.80.

CONCLUSION: Severe maternal morbidity occurs in approximately 2.9 per 1,000 births, is most commonly the result of postpartum hemorrhage, and occurs more commonly in association with several identifiable patient characteristics.


Severe maternal morbidity occurs in approximately 2.9 per 1,000 births and is most commonly the result of postpartum hemorrhage.

Departments of Obstetrics and Gynecology, Northwestern University, Chicago, Illinois, Case Western Reserve University-MetroHealth Medical Center, Cleveland, Ohio, Columbia University, New York, New York, the University of Utah Health Sciences Center, Salt Lake City, Utah, the University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, the University of Texas Southwestern Medical Center, Dallas, Texas, the University of Pittsburgh, Pittsburgh, Pennsylvania, The Ohio State University, Columbus, Ohio, the University of Alabama at Birmingham, Birmingham, Alabama, the University of Texas Medical Branch, Galveston, Texas, Wayne State University, Detroit, Michigan, Brown University, Providence, Rhode Island, the University of Texas Health Science Center at Houston–Children’s Memorial Hermann Hospital, Houston, Texas, Oregon Health & Science University, Portland, Oregon, and the Medical University of South Carolina, Charleston, South Carolina; the George Washington University Biostatistics Center, Washington, DC; and the Eunice Kennedy Shriver National Institute of Child Health and Human Development, Bethesda, Maryland.

Corresponding author: William A. Grobman, MD, MBA, Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University 250 East Superior Street, Suite 05-2175, Chicago, IL 60611; e-mail:

* For a list of other members of the NICHD MFMU, see the Appendix online at

The authors thank the following subcommittee members: Cynthia Milluzzi, RN, and Joan Moss, RNC, MSN, who participated in protocol development and coordination between clinical research centers; Elizabeth Thom, PhD, and Yuan Zhao, MS, for protocol/data management and statistical analysis; and Catherine Y. Spong, MD, and Brian M. Mercer, MD, for protocol development and oversight.

Dwight J. Rouse, MD, Associate Editor (Obstetrics) for Obstetrics & Gynecology, was not involved in the review or decision to publish this article.

The project described was supported by grants from the Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD) (HD21410, HD27869, HD27915, HD27917, HD34116, HD34208, HD36801, HD40500, HD40512, HD40544, HD40545, HD40560, HD40485, HD53097, HD53118) and the National Center for Research Resources (UL1 RR024989; 5UL1 RR025764) and its contents do not necessarily represent the official views of the NICHD, National Center for Research Resources, or the National Institutes of Health.

Financial Disclosure The authors did not report any potential conflicts of interest.

© 2014 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.