Value of the maternal interleukin 6 level for determination of histologic chorioamnionitis in preterm delivery.

The present study examined whether maternal serum cytokine levels are useful for the diagnosis of histologic chorioamnionitis. The blood samples of 29 women who delivered preterm between 22 and 34 weeks of gestation were collected at delivery, and placentas were histopathologically examined for chorioamnionitis. The interleukin (IL) 6 titer was higher in 18 mothers with histologic chorioamnionitis (median 12.0 pg/ml, range 4.9-63.5 pg/ml) than that in 11 mothers without histologic chorioamnionitis (median 3.5 pg/ml, range 1.7-14.9 pg/ml; p < 0.0001). The C-reactive protein (CRP) titer also differed significantly between these two groups (chorioamnionitis group: median 5.2 mg/dl, range 0.1-12.3 mg/dl; no chorioamnionitis group: median 0.2 mg/dl, range 0.1-0.5 mg/dl; p = 0.0001). The IL-6 titer showed better clinical diagnostic indices and a higher odds ratio (9.78, 95% confidence interval 1.50-63.82) than did CRP (3.26, 95% confidence interval 1.22-8.67). The levels of IL-8, monocyte chemotactic and activating factor, and soluble IL-6 receptor did not differ between the two groups. These data suggest that the level of maternal serum IL-6 is more useful than other markers, including CRP, for the identification of women at risk of impending preterm labor with histologic chorioamnionitis.