Pregnancy & Birth
Fetal Monitoring
Whether you have your baby in a birthing center, in the hospital, or at home, your provider will monitor your baby’s heartbeat to see how the baby is tolerating labor. Your baby’s heart rate will generally range between 110 and 160 beats per minute. During a contraction, the flow of blood to the baby is reduced, and as a result, the baby’s heart rate may temporarily go down.
Your provider can listen to the heart rate intermittently or continuously. Most hospitals will require 30 minutes of external fetal monitoring to obtain a baseline reading of your baby’s heart rate and response to contractions. From there, your baby’s heartbeat can be monitored periodically. Continuous fetal heart rate monitoring is not necessary in most births.
Intermittent Monitoring
Intermittent monitoring can be done with a fetoscope (a special stethoscope), or with a Doptone, a handheld device that uses ultrasound to detect and transmit the baby’s heart rate. Intermittent fetal heart rate monitoring is done by listening to the baby’s heartbeat through and right after a contraction for about 2 minutes every 5 to 30 minutes during labor, depending on the stage of labor you are in.
Continuous Monitoring
Continuous external electronic fetal heart rate monitoring involves placing two recording devices, held by soft belts, on your abdomen. One device detects the fetal heart rate and the other detects the uterine contractions. The baby’s heart rate and your contractions show up as peaks and valleys on a screen and on a paper printout, called the fetal heart rate tracing.
Usually, continuous fetal monitoring is done externally. If the external monitoring is not adequate or there are special concerns about the baby, internal monitoring is used. Internal monitoring is most often used to measure the baby’s heart rate, but sometimes a different kind of internal monitoring is used to measure the strength of your contractions.
To monitor the baby’s heartbeat internally, a small flexible wire, known as a fetal scalp electrode, is inserted through your vagina and attached to the baby’s scalp. The other end of the wire is attached to the monitor to provide a continuous recording of the baby’s heart rate.
An internal fetal monitor (IFM) produces the most accurate reading of your baby’s heart rate and response to contractions during labor. If an IFM is used, the newborn baby may have a small scab at the spot where the electrode was attached. This generally heals quickly and is not noticeable in a day or two.
Occasionally, your provider may want to measure internally the strength of your uterine contractions. To do this, a small catheter is inserted into the uterus through the vagina and the cervix and left in place. This pressure sensor is more accurate than the external monitor at measuring the intensity of the contractions.
Continuous monitoring usually limits a laboring woman’s ability to move, although in some instances a technique known as telemetry can allow a woman to walk while the fetal heart rate is being monitored continuously.
Intermittent Versus Continuous Monitoring
There is good evidence that continuous fetal monitoring in uncomplicated pregnancies has done nothing to improve outcomes for babies and mothers but has dramatically increased the cesarean section rate.3 Unfortunately, for a variety of reasons, continuous fetal monitoring has become the norm in many hospitals. (For more information on why this is so, see “Why Is Maternity Care Like This?” page 305).
Continuous fetal heart rate monitoring should be reserved for situations in which epidurals or Pitocin are being used and for women who have certain complications. If you are having a hospital birth and there is no clear- cut medical reason for you to have continuous monitoring, ask your provider to consider intermittent monitoring. (For more information on the limitations of continuous fetal heart rate monitoring, see “Variations in Fetal Heartbeat,” page 216.)
End of Excerpt.
Endnotes
3. Z. Alfi revic, D. Devane, and G.M.L. Gyte, “Continuous Cardiotocography (CTG) as a Form of Electronic Fetal Monitoring (EFM) for Fetal Assessment During Labour,” Cochrane Database of Systematic Reviews 2006, Issue 3. Art. No.: CD006066. DOI: 10.1002/14651858.CD006066. [Back to text.]
Excerpted from Chapter 10: Labor and Birth in Our Bodies, Ourselves: Pregnancy and Birth © 2008 Boston Women's Health Book Collective.
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