Chorioamnionitis and uterine function

Objective: To clarify the relationships between intrapartum chorioamnioniti s and abnormalities of uterine function, including labor abnormalities, ces arean delivery, and hemorrhage during parturition. Methods: We did a retrospective cohort study on 16,226 deliveries between 1 986 and 1996 that were identified from the University of California, San Fr ancisco Perinatal Database. Variables included maternal age, parity, birth weight, gestational age, epidural usage, oxytocin usage, cesarean delivery, labor abnormalities, length of labor stages, estimated blood loss, and cho rioamnionitis status. Analyses included chi(2), Student t test, and logisti c regression. Results: In the chorioamnionitis group, there was a statistically significa ntly higher proportion of women with labor abnormalities (relative risks [R Rs] 2.6-4.1), cesarean delivery (RR 3.3; 95% confidence interval [CI] 3.0, 3.5), hemorrhage after cesarean (RR 1.2; 95% CI 1.1, 1.3), and hemorrhage a fter vaginal delivery (RR 2.1; 95% CI 1.9, 2.4) compared with the nonchorio amnionitis group. Those findings stayed significant after multivariate anal ysis for various labor abnormalities (adjusted odds ratios [ORs] ranged 1.3 -2.1), cesarean delivery (adjusted OR 1.8; 95% CI 1.5, 2.1), hemorrhage aft er cesarean (adjusted OR 1.5; 95% CI 1.2, 1.8), and hemorrhage after vagina l delivery (adjusted OR 1.8; 95% CI 1.5, 2.1). Conclusion: Adverse associations between chorioamnionitis and labor abnorma lities, cesarean rate, and hemorrhage during parturition appear to be signi ficant, suggesting a deleterious effect of chorioamnionitis on uterine func tion. (Obstet Gynecol 2000;95:909-12. (C) 2000 by The American College of O bstetricians and Gynecologists).