Predictive value of maternal serum and vaginal interleukin-6 levels in preterm labor.

Objective: The aim of the current study was to evaluate the predictive value of maternal serum and vaginal interleukin 6 (IL-6) levels for preterm delivery before 37 gestational weeks in patients with preterm labor and to determine the probable relationship between IL-6 concentrations and delivery interval.

Methods: In this prospective study, maternal serum and vaginal IL-6 levels were measured in 40 patients with the diagnosis of preterm labor between the 28th and 36th gestational weeks (study group) and in 20 pregnant women between the same gestational weeks attending the antenatal clinic with no complaints (control group). The gestational age at the time of admission and delivery, as well as the delivery interval, were evaluated and compared with the concentration of IL-6 on admission.

Results: There were no significant relationships between maternal serum concentrations of IL-6 and preterm delivery. Vaginal IL-6 levels were significantly higher in the study group as compared with the control group (P < .001). The optimal cut-off value for vaginal IL-6 (172 pg/mL) gave a sensitivity level of 73.9% (95% confidence interval [CI], 67-82%) at a specificity of 100% (95% CI, 91-100%) with positive and negative predictive values of 94.1% and 83.7%, respectively. In the study group, the interval from collection to delivery was significantly shortened when the maternal vaginal IL-6 levels increased.

Conclusion: The ease of measurement, feasibility, cost-effectiveness, and success of identifying pregnancies at risk for preterm labor with vaginal IL-6 make this a useful biochemical marker for preterm labor and delivery.