A Validated Calculator to Estimate Risk of Chorioamnionitis in Laboring and Induced Patients at Term

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

• This calculator was created and validated for the prediction of developing chorioamnionitis.

• This calculator can be used to augment patient counseling.

• Predictive factors were identified and significantly associated with infection.

Keywords

calculator - chorioamnionitis - induction - infection - labor

Note

Poster Presentation for this study was held at the Society for Maternal-Fetal Medicine, The Pregnancy Meeting, February 11 to 14, 2024.

Condensation

A predictive model has been validated to estimate the risk of chorioamnionitis among individuals in labor.

Ethical Approval

The authors have obtained both informed consent and ethics committee approval for studies on patients, patient records, or volunteers (Institutional Review Board CC#39028).

Publication History

Received: 09 August 2024

Accepted: 12 September 2024

Accepted Manuscript online:
13 September 2024

Article published online:
08 October 2024

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