Abstract
Objective
Chorioamnionitis is associated with neonatal morbidity and infection-related mortality,
but our ability to predict intrapartum infection is limited. We sought to derive and
validate a prediction model for chorioamnionitis among patients presenting to labor
and delivery at term.
Study Design
This was a planned secondary analysis of a large cohort study from 2014 through 2018
at an academic tertiary care center. To derive a prediction model for chorioamnionitis,
we limited our analysis to full-term (≥37 weeks) patients with a singleton gestation
undergoing labor induction and presenting in labor. Both nulliparous and multiparous
patients were included. Patients with a planned cesarean delivery, fever on admission,
or missing data were excluded. The model was derived using multivariable logistic
regression. Refinement of the prediction model with internal calibration was performed.
External validation was performed utilizing a publicly available database (Consortium
on Safe Labor) and applying the same inclusion and exclusion criteria. The discriminative
power of each model was assessed using a bootstrap, bias-corrected area under the
curve.
Results
The chorioamnionitis rates in the derivation and external validation groups were 5%
(1,005/19,966) and 5.8% (n = 3,005/52,171), respectively. In multivariable modeling, maternal age, nulliparity,
gestational age, smoking status, group B Streptococcus colonization, hours ruptured, number of cervical exams, length of labor, epidural
use, internal monitoring, and meconium were significantly associated with infection.
A calculator was created and externally validated with an area under the curve of
0.82 (95% confidence interval, 0.81–0.82). External validity was further confirmed
with a calibration intercept of 0.81.
Conclusion
This is the first infection calculator created and validated for the prediction of
developing chorioamnionitis in patients undergoing induction of labor at term. This
calculator can be used to augment patient counseling and guide intrapartum infection
surveillance in laboring patients.
Key Points
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This calculator was created and validated for the prediction of developing chorioamnionitis.
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This calculator can be used to augment patient counseling.
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Predictive factors were identified and significantly associated with infection.
Keywords
calculator - chorioamnionitis - induction - infection - labor
