Electronic Fetal Heart Monitoring
Electronic fetal heart monitoring is done during pregnancy, labor, and delivery to keep track of the heart rate of your baby (fetus) and the strength and duration of the contractions of your uterus. Your baby's heart rate is a good way to tell whether your baby is doing well or may have some problems.
Two types of monitoring-external and internal-can be done.
You may have external monitoring at different times during your pregnancy, or it may be done during labor.
External monitoring can be done by listening to your baby's heartbeat with a special stethoscope. More often, external monitoring is done using two flat devices (sensors) held in place with elastic belts on your belly. One sensor uses reflected sound waves (ultrasound) to keep track of your baby's heart rate. The other sensor measures the duration of your contractions. The sensors are connected to a machine that records the information. Your baby's heartbeat may be heard as a beeping sound or printed out on a chart. The frequency and duration of your uterine contractions are usually printed out on a chart.
External monitoring is used for a nonstress test, which records your baby's heart rate while your baby is moving and not moving. A nonstress test may be combined with a fetal ultrasound to evaluate the amount of your amniotic fluid.
External monitoring is also done for a contraction stress test, which records changes in your baby's heart rate when you have uterine contractions. It may be done to check on your baby's health if your baby does not move enough during a nonstress test. It may help predict whether your baby can handle the stress of labor and vaginal delivery.
Sometimes external monitoring is done remotely (called telemetry), without your needing to be connected by wires to a machine. At some hospitals, the sensors can send the information about your baby's heart rate and your uterine contractions to a remote monitor, usually at a nurse's station. Remote monitoring allows you to walk around freely.
Internal monitoring can be done only after your cervix has dilated to at least 2 centimeters (cm) and your amniotic sac has ruptured. Once started, internal monitoring is done continuously.