Association between Fetal Heart Rate Monitoring during Labor and Neonatal Acidosis in Full-Term Newborns: A Retrospective Multicenter Cohort Study

Introduction: Fetal heart rate monitoring during labor is used to study fetal well-being and predict neonatal acidosis of newborn. Fetal heart rate monitoring is analyzed by the obstetrical team and categorized according to the FIGO guidelines. An important limitation of this diagnostic tool is an inter- and intra-observer variability, leading to subjective cardiotocography interpretation and classification. Our objective was to study the association between the categories of fetal heart rate analysis (according to FIGO classification) and neonatal acidosis of full-term newborns. Study design: This is a multicenter retrospective cohort study conducted between 2014 and 2018 in the Grand-Est region. We searched and included retrospectively children hospitalized in a pediatric intensive care unit in one of the participating hospitals with an ICD-10 coding type “P91.6” corresponding to “Hypoxic Ischemic Encephalopathy”. Maternal, pregnancy, delivery, and newborn characteristics were collected and compared by univariate logistic regression with multiple imputation. Odds Ratio and 95% confidence intervals (CI) were calculated using the model and presented. Multiple imputation with m = 100 imputations was tested, using Rubin rules to combine the results. Results: 55 patients were included in the study. Fetal heart rate tracings classified in Category 3 as “pathological” according to FIGO guidelines were significantly associated with an increased risk of severe neonatal acidosis. Late decelerations and bradycardia during labor were associated with severe neonatal acidosis. Conclusion: Severe neonatal acidosis may be suspected by interpretation of fetal heart rate during labor. Fetal bradycardia and late decelerations are predictive of the severity of neonatal acidosis. This study emphasizes the need to screen severe neonatal acidosis and allows the identification of populations most at risk. Repeated team training and upgrading of fetal heart rate study would further reduce the incidence of neonatal acidosis.