Fetal Monitoring
Fetal monitoring is a method of electronically monitoring labor. This method continuously records the baby's heart rate, the uterine contractions and the response of the baby's heart rate to the contractions. This information helps physicians to evaluate progress in labor and the response of the baby to labor.
Each time the uterus contracts, blood flow to the placenta decreases and the amount of oxygen the baby receives from the mother decreases. The baby must live off the oxygen already in his blood. Ordinarily, the baby has enough oxygen to carry him through the contraction until he can get more from the mother before the next contraction starts. When the baby has difficulty getting oxygen, changes in the baby's heart rate alert the health-care professionals to take action to help correct the situation.
Mothers in labor can be monitored both externally and internally. External monitoring is virtually painless and generally simple. To obtain the baby's heart rate and the mother's uterine contractions, two monitor leads are placed on the abdomen outside the uterus by soft velcro straps. Lubricant may be placed on the abdomen where the baby's heart rate is heard to help pick up the sound. Ultrasonic waves detect heart action and obtain the baby's heart rate.
A normal baby's heart rate tracing looks like a choppy, irregular line. An average baby's heart rate is 110 to 160 beats per minute. Physicians observe the tracings for accelerations and decelerations of the heart rate, which indicate how well the baby is responding to the stress of labor.
The external uterine contraction lead detects contractions by a pressure button. The machine converts this pressure to a graphic display on the lower portion of the paper.
There are some disadvantages to external monitoring. The monitor may not be able to clearly pick up the baby's heart rate or the uterine contractions because of the baby's position or the size of the mother's abdominal wall.
The external monitor does not show how strong the contractions are, which may be important to know if labor is slow. Another disadvantage is that the mother cannot move around well; she may need to remain in one or two positions, which can be tiring.
If external fetal monitoring does not provide the doctor with enough information about the response of the baby's heart rate to the stress of the labor contractions, internal fetal monitoring may be used. This consists of a tiny electrode that is applied directly to the skin of the baby's head (IFM) and a thin plastic catheter that is inserted into the uterus (IUPC). This catheter is placed between the baby and the uterine wall. Internal monitoring is a much more accurate way of determining the baby's heart rate and the frequency, strength and duration of the contractions.
Last Updated: September 24, 2009
