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Risk Factors for Postcesarean Maternal Infection in a Trial of Extended-Spectrum Antibiotic Prophylaxis

Boggess, Kim A. MD; Tita, Alan MD; Jauk, Victoria MPH; Saade, George MD; Longo, Sherri MD; Clark, Erin A. S. MD; Esplin, Sean MD; Cleary, Kristin MD; Wapner, Ronald MD; Letson, Kelli MD; Owens, Michelle MD; Blackwell, Sean MD; Beamon, Carmen MD, MPH; Szychowski, Jeffrey M. PhD; Andrews, William MD, PhDfor the Cesarean Section Optimal Antibiotic Prophylaxis Trial Consortium

doi: 10.1097/AOG.0000000000001899
Contents: Original Research

OBJECTIVE: To identify maternal clinical risk factors for postcesarean maternal infection in a randomized clinical trial of preincision extended-spectrum antibiotic prophylaxis.

METHODS: We conducted a planned secondary analysis of a randomized clinical trial. Patients were 24 weeks of gestation or greater and delivered by cesarean after a minimum of 4 hours of ruptured membranes or labor. All participants received standard preincision prophylaxis and were randomized to receive azithromycin or placebo. The primary outcome for this analysis is maternal infection: a composite outcome of endometritis, wound infection (superficial or deep), or other infections occurring up to 6 weeks postpartum. Maternal clinical characteristics associated with maternal infection, after controlling for azithromycin assignment, were identified. These maternal factors were included in a multivariable logistic regression model for maternal infection.

RESULTS: Of 2,013 patients, 1,019 were randomized to azithromycin. Overall, 177 (8.8%) had postcesarean maternal infection. In the final adjusted model, compared with the reference groups, women of black race–ethnicity, with a nontransverse uterine incision, with duration of membrane rupture greater than 6 hours, and surgery duration greater than 49 minutes, were associated higher odds of maternal infection (all with adjusted odds ratios [ORs] of approximately 2); azithromycin was associated with lower odds of maternal infection (adjusted OR 0.4, 95% confidence interval 0.3–0.6).

CONCLUSION: Despite preincision azithromycin-based extended-spectrum antibiotic prophylaxis, postcesarean maternal infection remains a significant source of morbidity. Recognition of risk factors may help guide innovative prevention strategies.


Black race–ethnicity, a nontransverse uterine incision, ruptured membranes greater than 6 hours, and surgery longer than 49 minutes are associated with postcesarean infection.

University of North Carolina at Chapel Hill, Chapel Hill, North Carolina; the University of Alabama at Birmingham, Birmingham, Alabama; the University of Texas Medical Branch, Galveston, Texas; Oshner Health System, New Orleans, Louisiana; the University of Utah and Intermountain Health–LC, Salt Lake City, Utah; Columbia University, New York, New York; Mission Hospital, Asheville, North Carolina; the University of Mississippi at Jackson, Jackson, Mississippi, the University of Houston at Houston, Houston, Texas; and WakeMed Physician Practices, Raleigh, North Carolina.

Corresponding author: Kim A. Boggess, MD, Maternal-Fetal Medicine Division, Department of Obstetrics and Gynecology, University of North Carolina at Chapel Hill, 3010 Old Clinic Building, Campus Box 7570, Chapel Hill, NC 27599; email:

Supported by a grant (HD64729) from the Eunice Kennedy Shriver National Institute of Child Health and Human Development; study medication (azithromycin) was provided by Pfizer through an investigator-initiated grant.

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

Presented in part at the 36th annual meeting of the Society for Maternal-Fetal Medicine, February 2–7, 2016, Atlanta, Georgia.

© 2017 by The American College of Obstetricians and Gynecologists. Published by Wolters Kluwer Health, Inc. All rights reserved.