Intrapartum fever at term: serum and histologic markers of inflammation.

Abstract

This study was undertaken to determine whether intrapartum fevers at term are associated with markers of acute inflammation in maternal, fetal, and placental compartments. Term cases with intrapartum fever (temperature >/=100.4 degrees F) were recruited with gestational age-matched controls. Maternal serum and umbilical vein blood were collected and assayed for interleukin-6 (IL-6) levels. Placentas were examined for histologic chorioamnionitis. Demographic and clinical data were collected and compared between cases and controls. Forty-seven case-control pairs were analyzed. Maternal IL-6 levels were higher in cases than in controls (median of 145 pg/mL vs 42 pg/mL, P <.0001). Umbilical vein IL-6 levels also were higher in cases than controls (median 9 pg/mL vs 3.5 pg/mL, P =.01), but more than half of levels in cases were below 11 pg/mL. Only 31.1% of febrile cases had moderate or severe histologic chorioamnionitis. Multivariable logistic regression identified maternal serum IL-6 levels, nulliparity, and number of vaginal examinations as the major predictors of intrapartum fever at term. The maternal inflammatory response as measured by maternal serum IL-6 levels is a strong marker for term intrapartum fever. The much weaker association of fetal and placental inflammatory responses suggest a smaller than expected contribution of intra-amniotic inflammation to term intrapartum fevers.