There are a number of uterine and fetal monitors available for pre-labor measurement of fetal activity. These fetal monitors are useful for a variety of reasons, ranging from parents who need to monitor their unborn baby for medical reasons to those who are just curious or the dad who can’t make it to the doctor’s office to hear the heartbeat.
Some fetal monitors, like the SpaceLabs AM66 and the Hewlett Packard 8040, are all-inclusive devices that monitor uterine and fetal activity of your baby right in the home and print out a graph of the activity using a printer directly on the face of the device.
With an optional modem board, these fetal monitors can also transmit the data to a central receiving station via a phone line. Uterine activity and fetal heart rate is monitored externally (with an option for internal monitoring) on the fetal monitor using an ultrasound tocotransducer strapped to the abdomen of the patient. This tocotransducer sends sound waves into the maternal abdomen and detects echoes coming from moving objects within. The fetal monitor analyzes these echoes, picking out indications of fetal heart motion, and uses the rhythm of the motions to compute the heart rate. At the same time, the tocotransducer detects uterine activity by sensing changes in tension on the abdomen. In addition, the mother holds a marker cable, similar to a bolus cord, and presses the button whenever uterine activity is detected; this places a mark on the graph so that the heartbeat of the fetus and the uterine activity can be correlated.
Doppler fetal monitors, on the other hand, utilize the frequency of ultrasonic waves reflected from a moving surface (the fetus) and use the difference between this frequency and that of incident waves to calculate the fetal heart rate. Doppler fetal monitors range from small hand-held units with headphones operating at low frequencies (approx. 3 MHz) with no memory or print capabilities, to sophisticated units measuring over a broad frequency range and providing activity history and printouts. Hand-held Doppler fetal monitors available include the IMEX Pocket-Dop II and the SpaceLabs DOP-1.
The FDA does regulate the sale and rental of fetal monitors for home use (as it does for hospital use). As always, experts recommend dealing only with a company that is monitored and certified by the FDA.
On average, fetal monitors can pick up heartbeats when the baby is 10-12 weeks along. This is the age when most doctors do it, and while some fetal monitors may be able to pick up the heartbeat at an earlier stage, fetal monitors can cause undue stress for the still developing fetus.
BabyBeat, a company that manufactures fetal monitors, sells fetal monitors at prices ranging from $449 to $549. The fetal monitors can also be rented for the duration of each pregnancy, and range from $30 to $49 a month. This way, you can return the monitor when you are finished, in case you have no use for it in the future.
The Coremetrics company (a division of GE) sells fetal monitors, which are more like home-use ultrasounds, for $2,995 to $3,995.
By Virginia Zignego