Fetus Monitoring Devices

Today, most women delivering in urban North American hospitals will be exposed to some type of monitoring device. Most hospitals will have you monitored electronically as soon as you are admitted to the maternity unit. There are various types of devices, all with a similar objective of assessing either fetal well-being or uterine contractions.

The two most commonly used devices are the fetal stethoscope and the electronic fetal monitor. There are two types of electronic monitors – the internal and the external monitor. Both send information to a machine that records a tracing of the fetus’s heart rate and the mother’s uterine contractions on graph paper.

Two Types of Devices

The external fetal monitor consists of two small ultrasonic devices strapped around the abdomen; one of them records fetal movements and the other records the muscle tightness of the abdomen or the uterine contractions.

The internal fetal monitor consists of an electrode (a small clip) that is inserted vaginally, under sterile conditions, and attached to the scalp of the fetus to measure its heart rate. A tube or catheter is used to measure the strength of the uterine contractions. Although the external fetal monitor is used more often, the internal fetal monitor is more sensitive and can provide important information for a high-risk mother.

The Doppler is another device you may see either on your regular obstetrical visits or during hospitalization. It is used to detect fetal heartbeats using sound waves. The heart rate is counted and recorded by listening to the fetal heartbeat through the abdominal wall. The fetal stethoscope was the only method of assessing fetal heart rate until the advent of portable Doppler machines in the late 1960s.

Although these technological advances help physicians and nurses to keep up with the mother’s status minute by minute, it is still common to assess the mother’s contractions manually by placing a hand on the fundus (muscular part of the uterus) until a contraction occurs.


The external fetal monitor is used in both low and high-risk cases to determine the fetus’s status and/or to determine how the baby is handling the stress of labor.

The internal monitoring device is used if external monitoring is not providing the desired results, or if there is a question about fetal well-being. It is only an option if your membranes are ruptured and delivery is expected within a few hours.

The electronic devices are often used for continuous monitoring during hospitalization, either for high-risk situations such as premature rupture of membranes, or during your actual labor. If your condition is stable and the fetal heart rate is stable, your monitor may be removed for a while so that you can get up.

When you are positioned for placement of the electronic monitor, two belts holding two separate devices (a tocotransducer and an ultrasonic transducer) will be placed on your abdomen. They will both be attached to a graph machine that gives a printout of your and your baby-to-be’s status.

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