During late pregnancy and labor, your doctor may want to monitor your baby’s heart rate and other functions. Fetal heart rate monitoring is a method of checking the rate and rhythm of the fetal heartbeat. The average fetal heart rate is between 110 and 160 beats per minute. The fetal heart rate may change as the fetus responds to conditions in the uterus. An abnormal fetal heart rate or rhythm may mean that your baby is not getting enough oxygen or there are other problems. An abnormal pattern also may mean that an emergency or cesarean delivery is needed.
How is fetal monitoring performed?
A type of stethoscope, called a fetoscope, is used to listen to the fetal heart beat. A device known as a handheld Doppler device can also be used to count the fetal heart rate. There are also continuous electronic fetal monitoring devices (often used during traditional childbirth) and intermittent fetal monitoring devices (sometimes used during more natural childbirth approaches) available in most hospitals.
Most fetal monitoring includes the following steps:
- Applying gel to the mother's abdomen; the gel acts as a medium for the ultrasound transducer.
- Attaching the ultrasound transducer to the abdomen with straps and transmitting the fetal heartbeat to a recorder; the fetal heart rate displays on a screen and is printed onto special paper.
- During contractions, an external tocodynamometer (a monitoring device that is placed over the top of the uterus with a belt) can record the patterns of contractions.
Sometimes, internal fetal monitoring is necessary for a more accurate reading of the fetal heart rate. Your amniotic fluid sac must be broken and your cervix must be partially dilated to use internal monitoring. Internal fetal monitoring involves inserting an electrode through the dilated cervix and attaching the electrode, called a fetal scalp electrode, to the scalp of the fetus.