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Published on: October 10, 2025
Intrapartum fever at term: serum and histologic markers of inflammation
John C Smulian1, Vineet Bhandari, Anthony M Vintzileos
1Division of Maternal-Fetal Medicine, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School/Saint Peter's University Hospital, New Brunswick, NJ, USA.
Objective:
This study was undertaken to determine whether intrapartum fevers at term are associated with markers of acute inflammation in maternal, fetal, and placental compartments.
Study Design:
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.
Results:
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.
Conclusion:
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.
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