Electronic fetal monitoring was developed during the 1970s to for use during labor to continuously measure the strength and frequency of uterine contractions and the fetal heartbeat. Using the information recorded on a strip of moving paper doctors hope to discover early if there are signs of distress and take necessary action to make birth safer for the baby.
Since the introduction of electronic fetal monitoring several controlled trials have demonstrated that use of a fetal stethoscope immediately after a contraction or during the interval between contractions is just as safe. While there has been no reduction in the fetal death rate nor those born with neurological abnormalities electronic fetal monitoring has shown a decrease in the number of babies who had neonatal seizures. This has prompted some proponents to champion the value of electronic fetal monitoring although it has been revealed that the type of neonatal seizure present in those babies produced no long-term health problems and occurred as a result of the mother receiving oxytocinOxytocin is a pregnancy hormone that both stimulates breast milk production and stimulates uterine contractions. Synthetic oxytocins have been created to induce labor.
Visit our comprehensive glossary for more pregnancy terms and definitions. in labor.
As the uterus contracts, pressure on the placentaThe placenta is a large disk shaped membrane responsible for providing nourishment to the fetus during pregnancy. It consists of three parts, the fetal part made up from the chorion membrane surrounding the fetus, the maternal part, formed from the decidua basalis layer of the uterine lining, and the intervillous space between the two plates. It is connected to the fetus by the umbilical cord and consists of tissue from both the mother and the embryo.
Its function is complex. It has been described as a simple organ that combines the functions of a kidney-dialysis machine, heart and lung machine and intravenous drip. It consists of enormous numbers of blood vessel branches that permit the exchange of nutrition and oxygen, from the mother's bloodstream to the fetus and the removal of wastes to the mother to be excreted. The placenta's remarkable quality is that it does so without the blood of the mother mixing with that of the baby.
It also is responsible for the production of vital hormones including, estrogen, progesterone, and human chorionic gonadotropin. After birth, the placenta is delivered, and is sometimes referred to as the afterbirth.
Visit our comprehensive glossary for more pregnancy terms and definitions. reduces the flow of oxygenated blood from the mother to the fetus for a few seconds. When this happens the fetal heart rate dips, but then returns to normal as the contraction ends. Most babies handle the reduced flow of oxygen without problem. If there is a delay before the fetal heart rate corrects it may be a sign the baby is distressed and the doctor will immediately evaluate the situation to ensure the health and safety of the baby.
Electronic fetal monitoring can be external, which can be performed at any time during labor. Internal fetal monitoring can only be done after the membranes have ruptured, either spontaneously or artificially, and the cervix has dilated at least 1 inch (2.5 cm).
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The external fetal monitor is attached to the mother's abdomen with two straps. One strap holds the tocodynamometer which is used to measure the frequency and strength of the uterine contractions. The other strap holds an ultrasound transducer similar to the Doppler scanner near the baby's heart to measure the fetal heartbeat.
The internal fetal monitor uses a small thin spiral shaped wire called a transducer, which is attached to the baby's scalp to measure the fetal heart rate. A cable connects the wire to the machine itself, although there is no risk of electric shock since no electricity passes through the transducer. A thin water filled tube called an intrauterine pressure catheter is inserted through the cervix into the uterus to measure the exact strength and frequency of the contractions which are recorded on the strip of moving paper.
The printout is recorded on a strip of moving paper, and shows the relationship between the fetal heart rate and the contractions. The machine can amplify the sound of the baby's heartbeat so that it can be clearly heard. Many monitors also use a flashing light to disply the frequency and intesity of the fetal heart rate and contractions although this is frequently turned off. Should there be a concern the machine will sound an alarm, although this is more often an indication of a problem with the machine than with the labor.
Electronic fetal monitoring is used in pregnancies where there is a high risk of fetal distress characterized by raised blood pressure, diabetes or other chronic disease. Continous monitoring is to be expected if there is a history of previous problems during labor.
The use of a synthetic oxytocinOxytocin is a pregnancy hormone that both stimulates breast milk production and stimulates uterine contractions. Synthetic oxytocins have been created to induce labor.
Visit our comprehensive glossary for more pregnancy terms and definitions. drip to stimulate contractions will also warrant the use of continuous electronic fetal monitoring since the the length, power and frequency of the contraction will need to be carefully observed. The use of electronic fetal monitoring during induction has lead to the discovery that only small amounts of the hormoneA complex chemical substance created in a part or organ of the body. When released it initiates or regulates activity in an organ or group of cells in another part of the body.
Hormones secreted by endocrine glands are transported through the bloodstream to their target organ. The amount of hormone secreted is regulated either by other hormones, by neurotransmitters, or simply when an excess of the organ's activity indicates a need to reduce the amount of the hormone produced.
Other hormones are produced locally by the organs themselves and are common in the digestive tract.
Visit our comprehensive glossary for more pregnancy terms and definitions. are enough to be effective.
During a high risk pregnancy electronic fetal monitoring will occur every fifteen minutes during the first stage of labor and every five minutes during the second stage. Electronic fetal monitoring is now considered routine in most hospitals during labor, and even low risk pregnancies can expect the procedure every thirty minutes during stage one and every fifteen minutes during stage two.
Electronic fetal monitoring will be introduced if there is any indication that the baby is not moving as much as it should. Alternatively Doppler scanning may used. If an external fetal monitor shows signs of abnormality the more accurate internal fetal monitor will be used.
While electronic fetal monitoring does permit movement, you will be confined to your bed while the machine is attached. Wireless electronic fetal monitoring is available and sometimes used during home birth although the risk of radio interference can contaminate the trace.
If using external fetal monitoring, care will need to be taken to ensure that the fetal heart rate signal is not lost as the baby or the mother moves. A similar loss of signal may occur if the internal electrode detaches from the the baby's scalp. A nurse will be adjusting the position of the electronic fetal monitor during the time that it is in use and some machines have transducers that track the position of the baby's heart automatically so the signal cannot be so easily lost.
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Many mothers find the straps that attach the transducer to the abdomen uncomfortable and even painful during labor. The discomfort is exacerbated by the limited movement. Birth coaches do benefit from the technology since they are able to watch the onset of a contraction and alert the mother as the peak approaches, greatly simplifying the adjustments necessary in maintaining effective breathing and relaxation techniques. Some mothers find that the monitor allows them to relax between contractions during a long labor and prepare more effectively for each contraction.
Detractors of electronic fetal monitoring express concerns that the machine receives more attention from medical staff during labor than the mother herself. Limited in movement and unable to use alternative pain relief methods such as a birth pool or transcutaneous electronic nerve stimulation (TENS machine), some women find electronic fetal monitoring make labor more stressful experience.
There are no known risks associated with this test. The data does needs to be interpreted by an experienced operator since there is a tendency to assume fetal distress at the first sign of abnormality and rush the mother into a cesarean section. Fetal blood sampling to measure the acidity of the baby's blood can be used to ascertain more accurately the distress of the fetus.
The test is performed during the first and second stages of labor. Monitoring will occur at fifteen minute intervals during the first stage of labor in a high risk pregnancy, and at five minute intervals during stage two. Low risk pregnancies can expect monitoring every thirty minutes during stage one and every fifteen minutes during stage two.
Fifty percent of all babies show signs of irregular heartbeat during labor. Experience and skill is needed to correctly identify signs of fetal distress from the printout or determine any abnormalities that do not show up on the machine.
Evidence suggests that babies actually sleep during labor, alternating between rapid eye movementA type of sleep pattern. REM sleep periods alternate with the nonrapid eye movement sleep periods and last from a few minutes up to half and hour.
REM sleep is when all dreaming occurs. Infants usually begin their sleep period with REM sleep whereas in adults REM sleep usually follows the four stages of nonrapid eye movement sleep.
Visit our comprehensive glossary for more pregnancy terms and definitions. (REM) sleep to deep sleep and back. This deep sleep sends manifests itself as a steady flat heartbeat on the monitor unaffected by the contractions. Should this occur, the doctor will try and wake the baby by touching the top of its head to stimulate a reaction on the monitor. The wide range of the fetal heartbeat, from 120 and 160 beats per minute, is a result of a surge in normal catecholamine, a stress hormone. If the heart beat falls outside that range, called bradycardia when it falls below and tachycardia when it rises above, it may lead to unnecssary intervention.
Should the electronic fetal monitor display any sign of fetal distress the baby's blood should be tested using fetal blood sampling to measure the acidity and confirm the diagnosis.
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