Intrapartum Fetal Heart Rate Monitoring

Introduction:

Fetal heart rate monitoring is a procedure to know how a baby's heart beats. A healthcare professional measures the baby’s heart rate during late pregnancy or labor to know how the baby is doing. The average fetal heart rate ranges between 110 to 160 beats per minute. However, it can vary by 5 to 25 beats per minute. The fetal heart rate may change depending on how the baby responds to changes in the uterus. An abnormal fetal heart rate can indicate that the baby is not getting sufficient oxygen or is having other problems.

There are two ways in which fetal heart rate is measured. They include:

• External fetal heart rate monitoring.

• Internal fetal heart rate monitoring.

What Is External Fetal Heart Rate Monitoring?

External fetal heart rate monitoring is a procedure that records the fetal heart rate through the mother's belly. It uses a device that listens to and records the baby's heart rate. In this technique, an ultrasound probe or transducer is fastened to the mother's abdomen. This transducer records and sends sounds of the fetal heart to a computer. The rate and rhythm of the baby's heartbeats are shown on the screen and printed on paper. External fetal heart rate monitoring is commonly done during the prenatal visit. It can also be checked continuously during labor and delivery.

What Is Internal Fetal Heart Rate Monitoring?

Internal fetal heart rate monitoring is done in cases where external fetal heart monitoring does not give satisfactory results or if the doctor needs to watch the baby closely during labor. In this procedure, a thin wire called an electrode is passed through the cervix and put on the baby's scalp. It is connected to a monitor, and the readings are recorded. It gives better results as the baby's movements do not affect the readings. However, the test can be done only when the amniotic sac (a fluid-filled sac surrounding the baby during pregnancy) has broken and the cervix is open.

During labor, the doctor monitors the fetal heart rate and uterine contractions. The rate of uterine contractions and the length of each contraction is monitored carefully. As internal fetal heart rate monitoring determines both parameters, the results can be compared. The pressure in the uterus can also be measured simultaneously. To record this, the doctor inserts a thin tube called a catheter through the cervix into the uterus, which sends the readings to a monitor.

When Is Fetal Heart Rate Monitoring Necessary?

A fetal heart rate monitoring may be necessary for the following conditions:

1. In high-risk pregnancy cases where the mother has diabetes or high blood pressure.

2. In cases where the growth and development of the baby are not up to the mark.

3. Fetal heart rate monitoring helps monitor how preterm labor medicines work (medicines that prevent labor from starting too early).

The other tests in which fetal heart rate monitoring is included are:

• Nonstress test, in which the fetal heart rate is measured as the baby moves.

• The contraction stress test measures uterine contractions and the fetal heart rate.

• A biophysical profile (BPP) includes a nonstress test and an ultrasound scan.

What Are the Factors That Affect Fetal Heart Rate During Labor?

A few factors may impact the fetal heart rate during labor. These include:

1. Uterine contractions.

2. Tests performed during labor.

3. Pain medicines or anesthesia administered during labor.

4. Pushing during the second stage of labor.

How to Get Ready for Fetal Heart Rate Monitoring?

• The healthcare provider will explain the procedure and ask to sign a consent form to perform the procedure.

• In a few cases, the fetal heart rate monitoring consent form may be a part of the general consent for birth.

• The healthcare provider must be informed about allergies to medicines, anesthesia, latex, or tape.

• In cases where fetal heart rate is monitored along with other tests, the mother may be instructed to have a meal before the procedure to make the baby more active.

• The doctor will inform prior that the amniotic sac has to be broken and the cervix has to be dilated several centimeters before performing the procedure to place the internal device.

• Any other general instructions given by the doctor must be followed.

What Happens During Fetal Heart Rate Monitoring?

The following process occurs during fetal heart rate monitoring:

• External Fetal Heart Rate Monitoring:

1. After wearing a hospital gown, the patient is asked to lie on the examination table.

2. Next, the healthcare provider will apply a clear gel on the abdomen and use a transducer on the skin till a fetal heartbeat is detected.

3. The sound of the heartbeat can be heard through a doppler or an electronic monitor.

4. During labor, the provider may opt for continuous monitoring of the fetal heart rate based on the mother and baby’s condition. A waist belt can be used to hold the transducer in place, and the transducer is connected to the monitor through a cable.

5. Once the procedure is completed, the doctor will wipe off the gel.

• Internal Fetal Heart Rate Monitoring:

1. The patient is asked to change into the hospital gown and lie on the labor bed.

2. The legs and feet are positioned like that for a pelvic examination.

3. The healthcare provider will perform a vaginal examination by placing a gloved finger to check how much the cervix has dilated.

4. If the amniotic sac appears to be intact, the provider may break it open with special tools, and the patient will feel a warm fluid flowing out of the vagina.

5. After this, the provider can feel the baby's head through the cervix.

6. The provider will then pass a thin tube through the vagina with a wire at its end, insert it into the baby's head and remove the catheter.

7. The wire is attached to a monitor and is held in place with the help of a band around the thigh.

8. The doctor will remove the wire once the baby is born.

What Happens After the Test?

The patient can return to normal activities and diet after external fetal heart rate monitoring, and no special care is required. However, after internal fetal heart rate monitoring, the doctor may look for bruises, cuts, or infections on the baby's scalp and clean the site with an antiseptic, if required.

Conclusion:

Fetal heart rate monitoring is a procedure done to assess the functioning of the fetal heart by measuring the heartbeats. It is done as part of routine checkups during late pregnancy or labor. The test gives the healthcare provider an idea about the fetus's well-being. In addition, fetal heart rate monitoring tests can help assess the fetal condition and detect complications, if any.