ELEVATED AMNIOTIC-FLUID INTERLEUKIN-6 LEVELS DURING THE EARLY 2ND TRIMESTER ARE ASSOCIATED WITH GREATER RISK OF SUBSEQUENT PRETERM DELIVERY

PROBLEM: Subclinical intra-amniotic infection is often associated with preterm delivery and may precede it by several weeks. We tested the h ypothesis that Interleukin-6 (IL-6) may be elevated in the midtrimeste r amniotic fluid of pregnancies destined to deliver preterm. METHODS: A historical cohort study was designed to compare the amniotic fluid ( AF) concentrations of IL-6 at 14-20 weeks in a group of women subseque ntly delivering at less than or equal to 34 weeks (n = 13) with those of women delivering at term (n = 166). Included were singleton gestati ons with no evidence of fetal structural or chromosomal abnormalities, or maternal conditions known to be associated with preterm delivery ( n = 179). Levels of IL-6 were measured by immunoassay and correlated w ith demographic and pregnancy outcome information. Statistical analysi s included correlation, one-way ANOVA after log-transformation, contin gency tables, logistic regression, and receiver operator characteristi c (ROC) curve analysis. RESULTS: There was an inverse correlation betw een AF IL-6 levels at 15-20 weeks and gestational age at delivery (r = -0.16, P = 0.03). Women delivering at less than or equal to 34 weeks had significantly higher median AF IL-6 levels (570 pg/ml versus 330 p g/ml, P < 0.0001), rate of African American race (50% versus 12%, P = 0.004), and of infants with birth weights < 10th centile (31% versus 7 %, P = 0.02) than women delivering at greater than or equal to 37 week s. Logistic regression analysis showed that IL-6 was independently ass ociated with PTD at less than or equal to 34 weeks after controlling f or race and birth weight centiles (P = 0.039). CONCLUSIONS: AF IL-6 at 15-20 weeks can identify patients at risk for PTD at less than or equ al to 34 weeks, suggesting that a portion of PTD cases have inciting e vents that take place during the early second trimester.