Evaluating definitions for maternal fever as diagnostic criteria for intraamniotic infection in low-risk pregnancies

Background: Conflicting statements by stakeholders in obstetric care have suggested different criteria for defining peripartum fever and suspected intraamniotic infection, which have not been evaluated.

Methods: A case-control study of pregnancies between 35 and 41 weeks at a single tertiary care center between January 2016 and December 2017. Cases with pathology-confirmed chorioamnionitis were identified, and demographic data, risk factors, and neonatal outcomes were extracted from the medical record. The American College of Gynecology (ACOG) and National Institutes of Health (NIH) Workshop guidelines for identifying isolated maternal fever and suspected intraamniotic infection were applied, retrospectively. Odds ratios, sensitivity/specificity, and predictive value of each guideline for pathology-confirmed chorioamnionitis and for secondary outcomes of interest were determined.

Results: 943 mother-infant dyads were evaluated including 41 (4.3%) with pathology-confirmed chorioamnionitis. Among cases, 18 (43.9%) experienced any maternal temperature ≥38°C (100.4°F) with 12 (29.2%) and 8 (19.5%) cases meeting criteria for isolated maternal fever according to the ACOG and Workshop guidelines, respectively. Furthermore, the ACOG and Workshop guidelines correctly identified 6 (14.6%) and 3 (7.3%) of cases of pathology-confirmed chorioamnionitis with high agreement between definitions (κ = 0.63). Laboratory evaluation, antimicrobial exposure, and prolonged length of stay in offspring are substantially higher in cases as compared to controls.

Conclusions: Guidelines that rely on maternal fever definitions for the diagnosis of suspected intraamniotic infection exhibit high agreement with low sensitivity, but high specificity and negative predictive value for pathology-confirmed chorioamnionitis. Maternal temperature ≥38°C continues to drive clinical decision-making for both mother and offspring.