Background: The link between histologic acute chorioamnionitis and infection is well established in preterm deliveries, but\nless well-studied in term pregnancies, where infection is much less common.\nMethodology/Principal Findings: We conducted a secondary analysis among 195 low-risk women with term pregnancies\nenrolled in a randomized trial. Histologic and microbiologic evaluation of placentas included anaerobic and aerobic cultures\n(including mycoplasma/ureaplasma species) as well as PCR. Infection was defined as $1,000 cfu of a single known\npathogen or a $2 log difference in counts for a known pathogen versus other organisms in a mixed culture. Placental\nmembranes were scored and categorized as: no chorioamnionitis, Grade 1 (subchorionitis and patchy acute\nchorioamnionitis), or Grade 2 (severe, confluent chorioamnionitis). Grade 1 or grade 2 histologic chorioamnionitis was\npresent in 34% of placentas (67/195), but infection was present in only 4% (8/195). Histologic chorioamnionitis was strongly\nassociated with intrapartum fever .38uC [69% (25/36) fever, 26% (42/159) afebrile, P,.0001]. Fever occurred in 18% (n = 36)\nof women. Most febrile women [92% (33/36)] had received epidural for pain relief, though the association with fever was\npresent with and without epidural. The association remained significant in a logistic regression controlling for potential\nconfounders (OR = 5.8, 95% CI = 2.2,15.0). Histologic chorioamnionitis was also associated with elevated serum levels of\ninterleukin-8 (median = 1.3 pg/mL no histologic chorioamnionitis, 1.5 pg/mL Grade 1, 2.1 pg/mL Grade 2, P = 0.05) and\ninterleukin-6 (median levels = 2.2 pg/mL no chorioamnionitis, 5.3 pg/mL Grade 1, 24.5 pg/mL Grade 2, P = 0.02) at\nadmission for delivery as well as higher admission WBC counts (mean = 12,000cells/mm3 no chorioamnionitis, 13,400cells/\nmm3 Grade 1, 15,700cells/mm3 Grade 2, P = 0.0005).\nConclusion/Significance: Our results suggest histologic chorioamnionitis at term most often results from a noninfectious\ninflammatory process. It was strongly associated with fever, most of which was related to epidural used for pain relief. A\nmore ââ?¬Ë?activatedââ?¬â?¢ maternal immune system at admission was also associated with histologic chorioamnionitis.
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