RESUMEN
In this study we evaluated different markers of infection and their relationship to preterm delivery. Forty-four consecutive women with singleton pregnancies in uncomplicated preterm labor were investigated. C-reactive protein (CRP) in peripheral maternal blood, amniotic fluid cytokines, amniotic fluid leukocyte count, and amniotic fluid culture were performed in all patients. Thirty-six patients responded to standard tocolytic therapy and delivered after 34 weeks' gestation. In eight patients treatment failed and they delivered before 34 weeks' gestation. Two of these eight patients had a positive amniotic fluid culture for Ureaplasma urealyticum. The positive culture was accompanied by an elevated neutrophil count in the amniotic fluid. Elevated amniotic fluid levels of tumor necrosis factor (TNF) (more than 23 pg/mL), interleukin-6 (IL-6) (more than 2292 pg/mL) and interleukin-8 (more than 164 pg/mL) correlated with early preterm delivery. CRP levels in serum had a low sensitivity (38%) but a high specificity (94%) in predicting preterm delivery. This study indicates that preterm labor can be initiated by infection. Markers of infection obtained by amniocentesis have a better sensitivity and positive predictive value than noninvasive markers. Elevated IL-6 (more than 2292 pg/mL) seems to be the best predictor for preterm delivery, with a sensitivity of 75% and a specificity of 97%.