electronic fetal monitoring

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Electronic Fetal Monitoring



Electronic fetal monitoring (EFM) is a method for examining the condition of a baby in the uterus by noting any unusual changes in its heart rate. Electronic fetal monitoring is performed late in pregnancy or continuously during labor to ensure normal delivery of a healthy baby. EFM can be utilized either externally or internally in the womb.


The heart rate of a fetus undergoes constant adjustment as it responds to its environment and other stimuli. The fetal monitor records an unborn baby's heart rate and graphs it on a piece of paper. Electronic fetal monitoring is usually advised for high-risk pregnancies, when the baby is in danger of distress. Specific reasons for EFM include: babies in a breech position, premature labor, and induced labor, among others.
When electronic fetal monitoring was originally introduced in the 1960s and 1970s, the hope was that it would help physicians diagnose fetal hypoxia, or lack of oxygen, in time to prevent damage to the baby. This lack of oxygen, also known as perinatal asphyxia or birth asphyxia, is an important cause of stillbirth and newborn deaths. It occurs when there are less than normal amounts of oxygen delivered to the body or an organ and there is build-up of carbon dioxide in the body or tissue. A lack of blood flow to an organ can cause asphyxia. Perinatal asphyxia can occur a long time before birth, shortly before birth, during delivery, or after birth. If the interruption to the supply of oxygen is short, the baby may recover without any damage. If the time is longer, there may be some injury that is reversible. If the time period without oxygen is very long, there may be permanent injury to one or more organs of the body. It is important to detect any signs of asphyxia as soon as possible. One of the signs is an abnormal heart rate and rhythm in the unborn baby, which can be detected by electronic fetal monitoring.
The fetal monitor is a more intricate version of the machine that a health care provider uses to listen to a baby's heartbeat. The monitor that is used during prenatal visits just picks up the sound of the baby's heart beating. The fetal monitor also keeps a continuous paper record of the heart rate. In addition, the fetal monitor can record uterine contractions on the lower part of the paper strip. This helps the doctor or midwife determine how a baby is handling the stress of contractions. The normal pattern is for the baby's heartbeat to drop slightly during a contraction and then go back to normal after the contraction is over. EFM looks for any changes from this normal pattern, particularly if there is a drastic drop in the baby's heart beat or if the heart rate does not recover immediately after a contraction.
Because it is an indirect test, it is not perfect. When an adult complains to a provider about not feeling well, checking the heart rate is only one of many things that the doctor will do. With an unborn baby, however, checking the heart rate is basically the only thing that a doctor or midwife can do.
Fetal monitoring can be helpful in a variety of different situations. During pregnancy, fetal monitoring can be used as a part of antepartum testing. If the practitioner feels that a baby may be at increased risk of problems toward the end of pregnancy, a baby can be checked every week or every other week with a non-stress test. In this test, changes in the baby's heart rate are measured along with the fetus' own movements. The heart rate of a healthy baby should go up whenever she or he moves.
Fetal monitoring is used on and off during early labor. As labor progresses, more monitoring is often needed. Usually, as the time for delivery nears, the monitor is left on continuously since the end of labor tends to be the most stressful time for the baby.
A baby who is having trouble in labor will show characteristic changes in heart rate after a contraction
Electronic fetal monitoring (EFM) is performed late in pregnancy or continuously during labor to ensure normal delivery of a healthy baby. EFM can be utilized either externally or internally in the womb. The illustration above shows the internal procedure, in which an electrode is attached directly to the baby's scalp to monitor the heart rate. Uterine contractions are recorded using an intrauterine pressure catheter which is inserted through the cervix into the uterus.
Electronic fetal monitoring (EFM) is performed late in pregnancy or continuously during labor to ensure normal delivery of a healthy baby. EFM can be utilized either externally or internally in the womb. The illustration above shows the internal procedure, in which an electrode is attached directly to the baby's scalp to monitor the heart rate. Uterine contractions are recorded using an intrauterine pressure catheter which is inserted through the cervix into the uterus.
(Illustration by the Electronic Illustrators Group.)
(late decelerations). If a baby is not receiving enough oxygen to withstand the stress of labor and delivery is many hours away, a cesarean section (C-section) may be necessary.


Using the external fetal monitor is simple and painless. Two elastic belts are placed around the mother's abdomen. One belt holds a listening device in place while the other belt holds the contraction monitor. The nurse or midwife adjusts the belts to get the best readings from each device.
Sometimes, it is difficult to hear the baby's heartbeat with the external monitoring device. Other times, the monitor may show subtle signs of a developing problem. In either case, the doctor or midwife may recommend that the external belt be replaced with an internal monitor.
The internal monitor is an electronic wire that rests directly on the baby's head. The provider can place it on the baby's head during an internal exam. The internal monitor can only be used when the cervix is already open. This device provides a more accurate record of the baby's heart rate.


There are no special preparations needed for fetal monitoring.


External EFM poses no direct risks to the baby. However, because of being connected to the machine, the mother cannot walk around. This inactivity may prolong labor and reduce oxygen levels in the mother's blood, both of which can be detrimental to the unborn baby. Another problem is that electronic fetal monitoring seems to be associated with an increase in caesarian deliveries. There is a concern that EFM can give false alarms of distress in the baby, and that this can lead to unneeded caesarians. With internal monitoring, there is a higher risk for infection. For these and other reasons, the United States Preventive Services Task Force states that there is some evidence that using electronic fetal monitoring on low-risk women in labor might not be indicated. Many physicians, however, continue to use EFM routinely, and believe it to be of value in both low-risk and high-risk labors.

Normal results

An unborn baby's heart rate normally ranges from 120-160 beats per minute (bpm). A baby who is receiving enough oxygen through the placenta will move around. The monitor strip will show the baby's heart rate rising briefly as he/she moves (just as an adult's heart rate rises when he/she moves).
The baby's monitor strip is considered to be reactive when the baby's heart rate rises at least 20 bpm above the baseline heart rate for at least 20 seconds. This must occur at least twice in a 20-minute period. A reactive heart rate tracing (also known as a reactive non-stress test) is considered a sign of the baby's well being.

Abnormal results

If the baby's heart rate drops very low or rises very high, this signals a serious problem. In either of these cases it is obvious that the baby is in distress and must be delivered soon. However, many babies who are having problems do not give such clear signs.
During a contraction, the flow of oxygen (from the mother) through the placenta (to the baby) is temporarily stopped. It is as if the baby has to hold its breath during each contraction. Both the placenta and the baby are designed to withstand this condition. Between contractions, the baby should be receiving more than enough oxygen to do well during the contraction.
The first sign that a baby is not getting enough oxygen between contractions is often a drop in the baby's heart rate after the contraction (late deceleration). The baby's heart rate recovers to a normal level between contractions, only to drop again after the next contraction. This is also a more subtle sign of distress.
These babies will do fine if they are delivered in a short period of time. Sometimes, these signs develop long before delivery is expected. In that case, a C-section may be necessary.



Kripke, Clarissa C. "Why Are We Using Electronic FetalMonitoring?" American Family Physician May 1,1999.
Sweha, Amir, et al. "Interpretation of the Electronic FetalHeart Rate During Labor" American Family Physician May 1,1999.

Key terms

Breech presentation — Fetal position in which the buttocks come first.
Cesarean section c-section — Delivery of a baby through an incision in the mother's abdomen instead of through the vagina.
Hypoxia — An oxygen deficiency.

electronic fetal monitoring

Obstetrics The use of electronic devices during L&D to assess the baby's heartbeat and uterine contractions. See External fetal monitoring, Fetal monitoring, Internal fetal monitoring.

electronic fetal monitoring



The use of an electronic device to monitor vital signs of the fetus.
References in periodicals archive ?
For a sample of the professional debate, see the letters to the editor in Electronic Fetal Monitoring in Predicting Cerebral Palsy, 335 NEW ENG.
The authors conclude that electronic fetal monitoring is here to stay despite its many shortcomings (failure to interpret CTG traces, failure to incorporate the clinical picture, delay in taking action and poor communication and documentation standards).
The recommendation came after panel members voiced hope and concern--hope that the STAN S31 fetal heart monitoring system could decrease the false-positive rate of standard electronic fetal monitoring and thus reduce the rate of unnecessary cesarean sections, and concern that it could potentially do the opposite and further increase the cesarean section rate.
Electronic fetal monitoring strips are frequently not kept as part of the hospital record and need to be requested separately.
A new study reports that electronic fetal monitoring (EFM) does not improve outcomes.
But electronic fetal monitoring (EFM), first introduced in the late 1960s, has increasingly become the technique of choice and is now used during three out of four deliveries in the United States.
Electronic Fetal Monitoring (EFM) reduces the risk of intrapartum fetal death from fetal hypoxia and prevents about one prenatal death per 1000 births.
They are refused VBACs, vaginal delivery of breech presentations, food and drink, and are forced to accept continuous electronic fetal monitoring (EFM), to name but a few.
Electronic fetal monitoring (EFM) is now routinely used to evaluate both the infant's heart rate as well as the pregnant woman's contractions.
However, the pervasive use of electronic fetal monitoring in obstetric practice has been challenging because of a lack of standardized nomenclature for heart rate assessment and clear guidance about how to interpret and manage various types of tracings.
They include chapters on tests during the antepartal period and fetal assessment and electronic fetal monitoring, reflecting the increase in intervention in maternity care.

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