Fetal Monitoring

External monitoring is the simplest way to monitor the fetal heartbeat. Your provider may use the following manual or electronic devices to do this:

• Handheld Doppler ultrasound: A Doppler ultrasound uses sound waves to measure your baby’s heart rate. Providers commonly use handheld Doppler devices during prenatal visits. Your provider will apply gel to your abdomen and move the probe over the gel. The device detects your baby’s heartbeat and displays it on a screen.
• Continuous Doppler ultrasound: During labor and delivery, your provider may choose continuous electronic fetal monitoring. For this, belts with sensors are strapped to your abdomen. A Doppler ultrasound tracks your baby’s heart rate, while another sensor measures the duration of your contractions and the intervals between them. These sensors may stay in place throughout your labor.

Another form of continuous monitoring, internal monitoring is when a small wire called an electrode is placed directly on the fetus, usually on the baby’s head. Your provider will place a sensor to your leg and guide the electrode through the cervix and into the uterus, attaching it to your baby’s scalp.

An intrauterine pressure catheter, a small tube that measures contractions, might also be inserted through the vagina and into the uterus. This type of monitoring can only be done after your water breaks, meaning the amniotic sac membranes have broken.

Your provider might choose to do internal monitoring for several reasons. Sometimes, external monitoring doesn’t pick up your baby’s heart rate well due to factors such as maternal weight or the mother frequently moving around. Additionally, internal monitoring also allows your provider to determine how strong your contractions are, not just how often, allowing for a more accurate assessment of labor.