Auscultation vs. fetal heart monitoring. (Guest Editorial).

Fetal heart rate monitoring is equally effective whether done electronically or by auscultation, according to many publications. In my opinion, however, electronic fetal heart rate monitoring is associated with higher intervention rates and fewer perinatal deaths due to asphyxia compared with intermittent or no auscultation.

Electronic fetal heart rate monitoring became routine in the mid-1970s based on the results of a number of retrospective studies. Seven retrospective comparisons with a total of more than 50,000 patients and seven historical control studies with a total of more than 20,000 patients found lower rates of stillbirth and neonatal mortality with routine electronic monitoring compared with selective monitoring or no monitoring.

More than six other retrospective studies in the 1970s compared electronic monitoring in approximately 20,000 patients to auscultation in about 50,000 patients matched by their risk for neonatal mortality. Again, better outcomes were found with electronic fetal heart rate monitoring even though the monitored patients had higher risk levels.

These are huge numbers of patients, but these are retrospective studies. The studies from the 19705 suggested that an adequate sample size would be at least 10,000 patients to have an 80% power to show a difference in perinatal mortality If you consider the technologic advances since the 1970s, you may need a sample of close to 18,000-20,000 patients to show a difference in perinatal mortality.

Of the nine randomized controlled trials comparing routine electronic fetal heart rate monitoring with intermittent auscultation, the first eight had design problems and produced mixed results about the usefulness of monitoring. Two studies found no differences in outcomes, one found improved neonatal status with electronic monitoring, and five found increased rates of interventions such as forceps use or cesarean section but no differences in perinatal outcomes.

Results from the first eight randomized controlled trials led to a widespread position that routine electronic monitoring and intermittent auscultation are equivalent.

Of these first eight controlled trials, seven lacked a power analysis and studied inadequately small numbers of patients--a few hundred in each arm. One study (the Dublin trial) ...