A disproportionate increase in IL-1β over IL-1ra in the cervicovaginal secretions of pregnant women with altered vaginal microflora correlates with preterm birth

Objective: This purpose of this study was to investigate the association between vaginal microflora, concentrations of interieukin-1beta (IL-1beta), and its natural receptor antagonist (IL-1ra) in the cervicovaginal discharge, and spontaneous preterm birth. Study design: Vaginal samples collected at 18 to 22 weeks' gestation from 207 women were analyzed to study qualitative and quantitative microbiologic aspects of vaginal microflora and IL-1beta and IL-1ra concentrations. Results: Among women colonized with anaerobic Gram-negative rods and/or Gardnerella vaginalis, an elevated IL-1beta concentration, or a diminished IL-1ra:IL-1beta ratio were associated with preterm delivery. A cut-off IL-1ra:IL-1beta ratio of < 8,632:1 optimally discriminated the subjects with subsequent spontaneous preterm deliveries from subjects who delivered at term, with a sensitivity of 78%, specificity of 51%, positive predictive value of 21%, and negative predictive value of 95%. Conclusion: A disproportionate increase in IL-1beta over IL-1ra in response to vaginal colonization with anaerobic Gram-negative rods and/or G. vaginalis at 18 to 22 weeks' gestation is associated with spontaneous preterm delivery. (C) 2004 Elsevier Inc. All rights reserved.