The relationship between cervical dilatation, interleukin-6 and interleukin-8 during term labor.
BACKGROUND: To determine interleukin-6 and interleukin-8 levels in amniotic fluid, retroplacental blood and maternal serum and relate these values with cervical dilatation in term labor. METHODS: Prospective study. n=78 healthy women undergoing term cesarean section, divided into four groups: controls, n=42, (elective cesarean section; no contractions, membrane rupture or cervical dilatation); latent labor, n=12, (latent phase labor; cervix <2 cm dilated); established labor, n=12, (active labor, cervix 2-5 cm); advanced labor, n=12, (active labor, cervix >5 cm). Interleukin-6 and interleukin-8 were determined by ELISA (pg/ml), placenta and placental bed biopsy examined histopathologically, and amniotic fluid also microbiologically. Results were expressed as median and ranges or mean and standard deviations, as appropriate. For statistical analysis, Mann-Whitney U-tests or Kruskal-Wallis tests were used as applicable (Statview 4.5). Power and linear regression analyses were performed. p<0.05 was considered significant, p<0.001 highly significant. RESULTS: Compared with controls, IL-6 and IL-8 increased significantly with cervical dilatation in all compartments tested for almost all labor groups (p<0.05 to p<0.0001). Significant changes were also seen between latent and advanced labor groups in some compartments (p<0.05), but not between established and advanced labor groups. Intrauterine infection was excluded in any of the patients clinically and on histopathological or microbiological analysis of placentae and amniotic fluid. CONCLUSIONS: In term labor without intraamniotic infection, interleukin-6 and interleukin-8 at the fetomaternal interface and in maternal serum rise significantly with cervical dilatation. These cytokines could be used as markers of active labor if vaginal examination is not applicable.