The Maternal-Fetal Medicine Units cesarean registry: chorioamnionitis at term and its duration-relationship to outcomes.

OBJECTIVE: The purpose of this study was to evaluate the relationship between chorioamnionitis and its duration to adverse maternal, fetal, and neonatal outcomes.

STUDY DESIGN: This was a 13-university center, prospective observational study. All women at term carrying a singleton gestation who underwent primary cesarean from January 1, 1999 to December 31, 2000 were eligible. Data abstraction was systematic and performed by trained research nurses. Selected adverse outcomes were compared between pregnancies with, and without, clinically diagnosed chorioamnionitis using relative risks (RRs) and 95% CIs. The duration of chorioamnionitis was stratified into 5 intervals (<or=3 h,>3-6 h,>6-9 h,>9-12 h, and>12 h), and respective outcomes compared by Mantel-Haenszel test for trend. Additionally, regression analysis was used to compute odds ratios (ORs) and 95% CIs for chorioamnionitis duration length as a continuous explanatory variable.

RESULTS: 16,650 pregnancies were analyzed, 1965 (12%) with chorioamnionitis, which was associated with significantly increased risks of maternal blood transfusion, uterine atony, septic pelvic thrombophlebitis, and pelvic abscess (RR 2.3-3.7), as well as 5-minute Apgar <or=3, neonatal sepsis, and seizures (RR 2.1-2.8). By test of trend, only uterine atony (P <.01), maternal blood transfusion (P=.03), maternal admission to intensive care unit (P=.02), and 5-minute Apgar <or=3 (P <.01) were associated with duration of chorioamnionitis. By logistic analysis, only uterine atony (OR for each hour of chorioamnionitis 1.03, 95% CI 1.00-1.06), 5-minute Apgar <or=3 (OR 1.09, 95% CI 1.00-1.16), and neonatal mechanical ventilation within 24 hours of birth (OR 1.07, 95% CI 1.01-1.12) were significantly associated with chorioamnionitis duration.

CONCLUSION: Chorioamnionitis was associated with increased rates of morbidity after cesarean at term. The duration of chorioamnionitis, however, was not related to most measures of adverse maternal or fetal-neonatal outcome.