Electronic fetal monitoring or EFM is an ultrasound technology used to monitor the baby's heart rate and the length, strength, and frequency of the mother's contractions during labor and birth. There are two main kinds of EFM: external and internal.
External Electronic Fetal Monitoring
With external EFM, two stretchy belts are placed across the abdomen. Each belt secures an electronic sensor to the mother's belly which is then attached by cords to the monitoring machine. One sensor monitors the baby's heart rate while the other sensor measures the mother's contractions. External EFM can be used either intermittently or continuously throughout labor. One disadvantage of this method is that the belts, sensors, and cords can seem bulky and make it difficult to change positions during labor. The belts and sensors must also be disconnected and reconnected each time the mother wishes to use the restroom or otherwise be up and moving around.
Internal Electronic Fetal Monitoring
Internal EFM consists of small cord inserted through the cervix and attached to a thin wire that screws into the top of the baby's head, allowing for the most accurate method of monitoring the baby. It is often used in conjunction with an intrauterine-pressure catheter, another internal device that is placed within the uterus to measure the mother's contractions. Internal EFM is a continuous monitoring method, though it does allow for more ease of movement than external EFM. The laboring mother must be dilated up to 1-2 centimeters and the amniotic sac must be ruptured in order to use this method.
Continuous electronic fetal monitoring carries clear benefits for mother's experiencing a high risk pregnancy or labor. Situations which indicate the use of continuous EFM include a baby with an abnormal heart rate, medical problems such as maternal high blood pressure, or the use of drugs during labor such as pitocin or epidural.
As with most technologies, EFM is not without it's risks. EFM uses ultrasound technology, which in and of itself has never been proven safe for use during pregnancy. Additionally, internal EFM carries the chance of injury to either the mother or the baby (if the device is placed incorrectly) and increases the risk of infection during labor.
Problems with Standard Practices of Fetal Monitoring
Though continuous electronic fetal monitoring is a widely accepted practice and used in many places for nearly every maternity ward patient, it was originally intended only for use with high risk pregnancies and births. There are no clear benefits to the use of continuous EFM during a normal (low-risk) labor and delivery. EFM is also subject to a wide range of interpretations. For example, one doctor may look at an EFM readout and determine that the baby is at no risk, while another may determine that the baby is in fetal distress and must be delivered quickly. Continuous EFM has also been linked with an increase of epidural anesthesia use and cesarean section rates.
There are alternatives available to electronic fetal monitoring. A Fetoscope or a Doppler can be used for intermittent monitoring of the baby's heartbeat, and is a great option for women experience a normal labor. Both methods offer the mother freedom of movement during labor and birth.
A new technology, called Telemetry Monitoring, also exists for mothers who need more continuous monitoring yet would like more ease of movement. This method uses a transmitter and radio waves, connected to your thigh, to transmit the baby's heart beat to the fetal monitor. There are no wires or cords, which allows the mother to move freely. Remember that continuous EFM for low-risk mothers is still questionable at best, but this can be a great option for mothers who need it.