Electronic fetal monitoring (EFM) involves the use of an electronic fetal heart rate (FHR) monitor to record the baby's heart rate. The FHR is picked up by means of an ultrasound transducer and the movement of the heart valves. Elastic belts are used to hold sensors against the pregnant woman's abdomen. The sensors are connected to the monitor and detect the baby's heart rate as well as the uterine contractions. The monitor then records the FHR and the contractions as a pattern on a strip of paper, called a tracing. Electronic fetal monitoring is frequently used during labor to assess fetal well-being. EFM can be used either externally or internally. Internal monitoring does not use ultrasound, is more accurate than electronic monitoring, and provides continuous monitoring for the high-risk mother. An internal monitor requires that the bag of waters be broken and that the woman is at least two to three centimeters dilated. It is used in high-risk situations or when it is difficult to obtain an accurate FHR tracing.
Telemetry monitoring has been available since the early 1990s but is not used in many hospitals as of 2004. Telemetry uses radio waves transmitted from an instrument on the mother's thigh, which allows the mother to remain mobile. It provides continuous monitoring and does not require the patient to be in bed continuously.
Besides EFM and telemetry, which is usually continuous, there is intermittent monitoring using a hand-held Doppler to assess the FHR. This method gives the mother freedom of movement during labor. Prior to electronic gadgetry a special stethoscope was used, called a fetoscope, which is rarely seen as of 2004 because it requires more skill to use. Research on the use of intermittent monitoring and continuous monitoring found no difference in fetal outcomes with intermittent monitoring. The use of continuous monitoring does result in a higher c-section rate partly because the tracing can be misinterpreted or because the mother usually requires more interventions when she cannot be mobile.
