Objective: To determine whether continuous intrapartum electronic fetal heart rate monitoring (EFM) is associated with decreased perinatal mortality and morbidity compared with intermittent auscultation.
Methods: The study was conducted simultaneously at two university hospitals in Athens, Greece (Alexandra and Marika Iliadi Hospitals) from October 1, 1990 to June 30, 1991. All patients with singleton living fetuses and gestational ages of 26 weeks or greater were eligible for inclusion. The participants were assigned to continuous EFM or intermittent auscultation based on the flip of a coin. Both groups were followed during labor according to the most recent ACOG guidelines. However, fetal scalp blood pH and crossover from one group to the other were not used.
Results: A total of 1428 patients were included, 746 in the EFM group and 682 in the auscultation group. There were no differences between the groups in erms of maternal age, gravidity, parity, gestational age, and number of antepartum high-risk factors. More patients monitored electronically received oxytocin for either augmentation (52.4 versus 38.1%; P = .0001) or induction (15.6 versus 7%; P = .0001). The length of labor was longer in the EFM group (first stage 6.1 +/- 4.3 versus 5.5 +/- 3.7 hours; P = .006; second stage 29.4 +/- 18.6 versus 26.9 +/- 16.9 minutes; P = .01). There was a higher incidence of nonreassuring fetal heart rate patterns in the EFM group (23.4 versus 10.7%; P = .0001) and a higher rate of surgical intervention (11.2 versus 4.8%; P = .0001). This difference pertained to both vacuum extraction (5.8 versus 2.4%; P = .002) and cesarean delivery for suspected fetal distress (5.3 versus 2.3%; P = .005). There were no differences in 1- and 5-minute Apgar scores, fetal acidosis at birth, need for neonatal resuscitation, neonatal intensive care unit admission, use of assisted ventilation, neonatal hospital stay, or any other neonatal complications. Two neonatal deaths occurred in he EFM group and nine perinatal deaths in the auscultation group (two intrapartum and seven neonatal deaths). The perinatal mortality rates were 2.6 per 1000 and 13 per 1000 total births, respectively (P = .04). The two deaths in the EFM group and three of the neonatal deaths in the auscultation group may not have been prevented by intrapartum monitoring; however, four neonatal deaths from the auscultation group occurred in depressed (5-minute Apgar scores less han 7), acidotic (cord artery pH at or below 7.13) infants. The perinatal death rate related to fetal hypoxia was significantly less in the EFM group (zero of 746 versus six of 682; P = .03).
Conclucion: In this controlled trial, intrapartum EFM, as the primary and only method of intrapartum fetal surveillance, was associated with decreased perinatal mortality due to fetal hypoxia but also with higher rates of surgical intervention for suspected fetal distress. Author-abstract.
Vintzileos, A. M. et al. 1993. Obstetrics & Gynecology 81:899-907.