Clinical understanding of the value of fetal heart rate monitoring has undergone dramatic changes in recent years. When fetal monitoring was first developed, medical scientists hoped the widespread use of this device would allow doctors and nurses to detect early signs of trouble during labor and delivery, prompting cesarean sections to prevent cerebral palsy. (Cerebral palsy is thought to be sometimes caused by inadequate oxygen to the fetus during pregnancy.)
In the 1970s and 1980s, doctors increased the number of cesarean sections based on some of the heart rate patterns described above, confident they would reduce the rate of cerebral palsy. Unfortunately, fetal heart rate monitoring has not lived up to that expectation. In the early-1970s, the rate of cesarean sections in the was about 5%. By the early-1990s, the rate of cesarean sections had risen nationwide to over 20%.
Unfortunately, recent surveys from several countries where fetal monitoring has been widely practiced have revealed no decline in the rate of cerebral palsy. Many studies comparing the traditional method of using a stethoscope to the newer method of electronic heart rate monitoring fail to show any reduction in cerebral palsy or any long-term neurological handicap among babies undergoing electronic fetal heart rate monitoring. One study in premature babies actually showed an increase in cerebral palsy among babies who underwent electronic fetal monitoring compared to those managed by a more traditional method. Although this does not mean that fetal monitoring causes cerebral palsy, it is very clear that fetal heart rate monitoring will not prevent cerebral palsy or neurologic injury to a baby.
It is now increasingly clear that most babies with traditionally worrisome fetal heart rate patterns tolerate these patterns perfectly well. On the other hand, babies who are developmentally abnormal before labor begins will probably show abnormal heart patterns during labor that may prompt a cesarean section. In most cases, the damage has been done at some point in the uterus before labor, rather than during the few hours of the labor and delivery process.
Is There Any Value in Electronic Fetal Monitoring?
Although fetal monitoring has not significantly reduced the rate of neurologic impairment in infants, it has almost eliminated fetal death during labor (stillbirth). Current electronic fetal heart rate techniques enable the birthing team to detect when the baby appears not to be tolerating labor well and needs to be delivered. In addition, the electronic monitor can help doctors and nurses detect changes in the baby's heart rate and/or the contraction pattern that suggest other complications that could cause injury or fatality. These include a prolapsed umbilical cord, placental abruption, or a fetal hemorrhage. In many hospitals, the electronic image from a patient's room can be transmitted to a central station where nurses can observe a bank of monitors. Thus, the mother can be assured that her baby is being watched carefully even when the nurse is not in the room.
Note about High-risk Pregnancies
In summary, fetal monitoring has been disappointing as a way to prevent cerebral palsy; however, while it may have contributed to many unnecessary cesarean sections over the past several decades, it has also contributed to the virtual elimination of fetal death during labor and delivery. Prevention of stillbirth is obviously a desirable goal, and thus electronic fetal heart rate monitoring remains a valuable part of the care of most women during labor and delivery.