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 (Reference fetus Opens New Window) and the strength and duration of the contractions of your Reference uterus Opens New Window. 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.

External monitoring

You may have Reference external monitoring Opens New Window Reference Opens New Window 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 Reference 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 Reference fetal ultrasound Opens New Window to evaluate the amount of your amniotic fluid.

External monitoring is also done for a Reference contraction stress test Opens New Window, 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

Internal monitoring can be done only after your Reference cervix Opens New Window has dilated to at least 2 centimeters (cm) and your Reference amniotic sac Opens New Window has ruptured. Once started, internal monitoring is done continuously.

For internal monitoring, a sensor is attached to your thigh with a strap. A thin wire (electrode) from the sensor is inserted through your vagina and cervix into your uterus. The electrode is then attached to your baby's scalp. Your baby's heartbeat may be heard as a beeping sound or printed out on a chart. Internal monitoring does not use reflected sound waves (ultrasound) for monitoring.

A small tube that measures uterine contractions may be placed in your uterus next to your baby. The strength and timing of your uterine contractions is usually printed out on a chart.

Internal monitoring is more accurate than external monitoring for keeping track of your baby's heart rate and your contractions.

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