During contractions, the blood flow to your baby is reduced causing the heart rate to drop temporarily. This is normal and healthy - it means your baby's body is working properly and handling contractions well. By monitoring the changes in heart rate, your caregivers hope to have warning if your baby is no longer handling contractions well.
Medications used during labor increase the likelihood that your baby will not tolerate contractions well. When you use medications to cause contractions or to relieve pain during contractions, your baby will be monitored continuously to ensure any changes in heart rate are recognized.
There are many ways to monitor the baby in labor. Your ability to choose any of these options will depend on their availablity at your birth place and the circumstances of your labor.
A fetoscope looks similar to a stethoscope, but has a larger bell to allow the user to hear the babies hear beat. It works by amplifying the sound of the heart beat, and can be used any time during labor. Not all birth places make a fetoscope available, and it can not be used when continuous monitoring is required.
The doptone is a hand held ultrasound tool. I works by sending a high frequency sound wave into your body, and then retrieving the sound wave as it bounces back. The doptone is useful underwater, where other monitoring tools might be damaged. Because it is hand-held, a doptone can not be used when continuous monitoring is required.
Electronic Fetal Monitor
The electronic fetal monitor (EFM) is an ultrasound device that records the baby's heart beat and the relative strength of a contraction on a strip of paper. This allows the care giver to see how the baby has been responding to contractions without having to hold a listening device onto mothers abdomen, or even be in the room. This has led to some criticism of the device by experts who feel that if a woman needs to be monitored, she should be monitored by a person who can respond immediately in the event of an emergency rather than 15 to 30 minutes later when the strip of paper is reviewed.
The EFM has other criticisms as well. Its use is associated with an increased cesarean surgery rate without a increase in the health of mother or baby. This may be due to the relatively high rate of false readings - the EFM reads fetal distress when none exists.
Another criticism is that the EFM requires the woman to be connected by a cord to a box. This limits mobility and makes it difficult to get into some positions. Sometimes a woman is asked to change her position specifically to allow the EFM to get a better reading.
Telemetry is an electronic fetal monitor without wires. It does not improve the false readings of an EFM, but it does eliminate many of the problems associated with mobility and positioning. Telemetry is not available in all hospitals.
Internal Fetal Monitor
The internal fetal monitor (IFM) uses an tiny electrode that punctures the baby's skin to get the most accurate reading of the baby's condition available. In some cases a pressure monitor will also be used to measure the relative strength of contractions. The electrodes are inserted through the vagina into the uterus. The wires will be taped to your leg so they do not get pulled out if you shift position.
The IFM requires that your bag of water be broken, which increases the pressure on your baby's head and increases your risk of dilating with a cervical lip (part of the cervix doesn't stretch back). It also requires that you lay relatively still to prevent pulling on the wires.
Types of Monitoring
Not all monitoring is the same. Depending on your situation, your options for types of monitoring may be limited.
Unless you are planning an unassisted home birth, having no monitoring is basically an impossibility. You are paying your health care provider to alert you if anything becomes unhealthy, and monitoring is one of the ways they do that.
With intermittent monitoring you will spend a designated amount of time being monitored, maybe so many minutes per hour or two, and the rest of the time will be free to move around. The monitoring may be done with a fetoscope, doptone or by attaching an electronic fetal monitor to you. It is sometimes necessary to remind nurses that you want to be taken off the electronic fetal monitor when you choose to use intermittent monitoring.
In some situations, such as when you choose to use a medication, it is necessary to monitor your baby continuously. This can be done with an electronic fetal monitor, telemetry unit or internal monitor. This option allows you the least mobility.
The risk of not monitoring would be that your baby may have a problem that goes undetected. The two most common problems in labor without medications are hemorrhage (mother does not stop bleeding fast enough after the placenta is out) and a baby who does not breathe right away after being born. Neither of these problems (which account for 75% of the 5% of problems in labor) are detectable or preventable with monitoring.
It has generally been assumed that the more you monitor, the better off the baby and mother will be. However, Henci Goer reports in The Thinking Woman's Guide to a Better Birth that studies have failed to find a link between increased monitoring and better outcomes. In fact, the studies have shown that continuous use of the electronic fetal monitor increases the chances of a cesarean surgery without the expected increases in health.
There are some experts who are concerned about the use of ultrasound in monitoring. They feel that it has not been fully tested to ensure safety.
Non-medical risks to monitoring are:
False readings may cause panic or fear
Discomfort due to restricted positioning
Discomfort due to breaking of bag of waters
Discomfort of EFM band attached to abdomen