Comparison of intrapartum electronic fetal heart rate monitoring versus intermittent auscultation in detecting fetal acidemia at birth

OBJECTIVE: Our purpose was to compare continuous intrapartum electronic fetal heart rate monitoring with intermittent auscultation for detecting fetal acidemia at birth. STUDY DESIGN: Data from a previously published randomized trial of electronic fetal heart rate monitoring versus intermittent auscultation were analyzed to identify any differences between the two methods in detecting fetal acidemia at birth. Fetal acidemia at birth was defined as the presence of cord blood arterial pH <7.15. RESULTS: A total of 1419 patients with umbilical cord blood acid-base measurements were identified, 739 in the electronic FHR monitoring group and 680 in the auscultation group. Electronic FHR monitoring had significantly better sensitivity (97% vs 34%, p< 0.001), lower specificity (84% vs 91%, p< 0.001), higher positive predictive value (37% vs 22%, p< 0.05), and higher negative predictive value (99.5% vs 95%, p< 0.001) in detecting fetal acidemia at birth. In addition, electronic FHR monitoring was significantly better in detecting all types of acidemia: metabolic (95.5% vs 26.5%, p< 0.001), mixed (95% vs 37.5%, p< 0.001), and respiratory (100% vs 41.5%, p< 0.001). CONCLUSION: These data suggest that electronic FHR monitoring is superior to intermittent auscultation in detecting fetal acidemia at birth.