High interleukin-16 concentrations in the early second trimester amniotic fluid: An independent predictive marker for preterm birth

Objective: Infection is believed to be one of frequent and important causes of preterm labor. We attempted to evaluate whether the level of inflammatory markers, e.g. interleukin-16 (IL-16), interleukin-18 (IL-18), and ferritin, in amniotic fluid at early second trimester can predict preterm birth. Methods: Amniotic fluid (AF) samples were collected from 350 pregnant women who had trans-abdominal amniocentesis for genetic indications at 16 to 20 weeks of gestation. AF levels of IL-16, IL-18 and ferritin levels were measured by immunoassay and were correlated with pregnancy outcomes. Results: Among the 350 pregnant women, 58 (16.6%) had preterm birth (<37 weeks gestation). AF levels of IL-16, IL-18, and ferritin were significantly higher in pregnant women with subsequent preterm birth. Multivariate analyses showed that a quartile higher of AF IL-16 level was significantly associated with preterm birth (OR: 3.09, 95% CI 1.52-6.27, p = 0.002). A receiver operating characteristic analysis revealed that an IL-16 cutoff value of 105 pg/ml was a reliable predictor of preterm birth (sensitivity, 90.2%; specificity, 52.7%; negative predictive value, 84.3%). Conclusion: It is feasible to predict preterm birth by measuring the AF levels of IL-16 especially for the pregnant women requiring genetic amniocentesis during early second trimester.