Interleukin-6 and Interleukin-8 in Cervical Fluid in a Population of Swedish Women in Preterm Labor: Relationship to Microbial Invasion of the Amniotic Fluid, Intra-amniotic Inflammation, and Preterm Delivery

Abstract

Preterm birth (PTB) remains the leading cause of perinatal morbidity and mortality and also is associated with cerebral palsy and suboptimal performance at school. Adverse outcomes are especially likely if there is intrauterine infection and inflammation. Because of its subclinical nature, however, the diagnosis depends on examining amniotic fluid, a relatively invasive procedure. In this study, amniotic fluid and cervical fluid were evaluated, and the presence in the latter of interleukin (IL)-6 and IL-8 was related to microbial invasion of amniotic fluid, intraamniotic inflammation, and PTB in women with singleton pregnancies who were in preterm labor before 34 weeks gestation and whose membranes were intact. Cervical fluid was sampled from the external cervical os within 12 hours of admission in 91 women and amniotic fluid in 56. The polymerase chain reaction technique was used to detect Ureaplasma urealyticum and Mycoplasma hominis. Interleukins 6 and 8 were estimated by enzyme-linked immunosorbent assay. Women had a median gestational age of 30 weeks at the time of the study; 38% delivered before 34 weeks gestation. No woman had clinical chorioamnionitis. Although the presence of aerobic and facultative aerobic bacteria did not relate to different interleukin levels in cervical fluid, both interleukins were significantly reduced in amniotic fluid. Half of the 50 patients examined for U. urealyticum and M. hominis in cervical fluid were positive, all but 2 of them for U. urealyticum. Mycoplasmas correlated with significantly higher levels of IL-6 in cervical fluid. IL-6 was detected in cervical fluid in 83% of patients and IL-8 in 100%. Women who delivered before 34 weeks gestation had significantly higher levels of both interleukins in cervical fluid than those who delivered later. The best cutoff levels for delivery within 7 days were 1.3 ng/mL for IL-6 and 7.7 ng/mL for IL-8. Interleukin levels in cervical fluid correlated with levels in amniotic fluid. For women in preterm labor, high levels of IL-6 and IL-8 in cervical fluid are predictive-to a moderate degree-of both intrauterine infection/inflammation and preterm delivery.