Microbial invasion and cytokine response in amniotic fluid in a Swedish population of women with preterm prelabor rupture of membranes

Background. Previous studies have shown an association between intra-amniotic microbial invasion and/or inflammation and spontaneous preterm birth. The aim of this study was to investigate the occurrence of intra-amniotic microorganisms and cytokines [interleukin (IL)-6 and IL-8] in a Swedish population, with low incidence of preterm birth, of women with preterm prelabor rupture of membranes and their correlation to preterm birth. Methods. Amniotic fluid was retrieved transabdominally from 58 patients with preterm prelabor rupture of membranes before 34 weeks of gestation. Polymerase chain reaction (PCR) analyses for Ureaplasma urealyticum and Mycoplasma hominis and culture for aerobic and anaerobic bacteria were performed. IL-6 and IL-8 were analyzed with enzyme-linked immunosorbent assay (ELISA). Results. Microorganisms in amniotic fluid were detected in 13 patients (25%). Patients with bacteria detected in the amniotic fluid had significantly higher levels of IL-6 and IL-8. An amniotic fluid concentration of IL-6greater than or equal to0.80 ng/ml [relative risk 1.93, 95% confidence interval (CI) 1.13-3.29, sensitivity 63%, specificity 75%] was associated with an increased risk of delivery within 7 days. There was also an association between IL-8 and preterm birth (<34 weeks). Conclusion. Intra-amniotic microbial invasion and inflammation in this population of Swedish women with preterm prelabor rupture of membranes were similar to data reported from populations with a higher incidence of preterm delivery. Amniotic IL-6 correlated to the presence of microorganisms and delivery within 7 days and IL-8 to delivery before 34 weeks.