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.
CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov, https://clinicaltrials.gov, NCT012235546.
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: email@example.com.
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.