Electronic fetal monitoring
The fetal monitor records an unborn baby's heart rate during pregnancy and labor and graphs it on a piece of paper. The fetal monitor is the best way to evaluate an unborn baby, and it is almost the only test to make sure that a baby is doing well during labor. During pregnancy, fetal monitoring can be usedas 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. Fetal monitoringis used on and off during early labor. As labor progress, more monitoring isoften 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 forthe baby. A baby who is having trouble in labor will show changes in heart rate after a contraction. 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 fetal monitor is simple and painless. Two elastic belts are placedaround the mother's abdomen. One belt holds a listening device in place whilethe 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 monitoring device. Other times, the monitor may show subtle signs of a developing problem. In either case, the doctor or midwife may recommend using an internal belt instead of the external belt. The internal monitor, an electronic wire that is placed on the baby's head during an internal exam, is more accurate but it can only be used when thecervix is already open.
An unborn baby's heart rate normally ranges from 120-160 beats per minute (bpm). A baby who is getting enough oxygen through the placenta moves around. The monitor shows the baby's heart rate rising briefly as he/she moves (just asan adult's heart rate rises when he/she moves). The baby's monitor strip isconsidered 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 leasttwice in a 20-minute period. A reactive heart rate tracing means that the baby is doing well. 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 thatthe baby is in distress and must be delivered soon. However, many babies whoare 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 oxygento do well during the contraction. The first sign that a baby is not gettingenough oxygen between contractions is often a drop in the baby's heart rate after the contraction. The baby's heart rate recovers to a normal level between contractions, only to drop again after the next contraction. This is also amore 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. Fetal monitoringis not a perfect test but it is the best test available to diagnose increased risks to an unborn baby at the end of pregnancy and during labor.