What Is Fetal Heart Rate Monitoring?
Fetal heart rate monitoring is a process that lets your doctor see how fast your baby’s heart is beating. If you’re pregnant, your doctor will want to make sure your baby is healthy and growing as they should. One of the ways they do that is to check the rate and rhythm of your baby’s heartbeat.
The doctor is most likely to do this later in your pregnancy and when you’re in labor. They may combine it with other tests for a closer look if you have diabetes, high blood pressure, or any condition that could cause problems for you and your baby.
Reasons for Fetal Heart Rate Monitoring
The doctor is more likely to use fetal heart rate monitoring when your pregnancy is high-risk. You may need fetal heart rate monitoring when:
- You have diabetes.
- You have high blood pressure.
- You’re taking medicine for preterm labor.
- Your baby isn’t growing or developing normally.
Types of Fetal Heart Rate Monitoring
The doctor can monitor your baby’s heartbeat in a couple of ways. They can listen for or electronically record the beats from outside your belly. Or once your water has broken and you’re in labor, they can thread a thin wire through your cervix and attach it to your baby’s head.
External monitoring (auscultation): If your pregnancy is going normally, the doctor likely will check your baby’s heart rate from time to time with a special stethoscope or a hand-held device called a Doppler ultrasound. Doctors sometimes call this type of fetal heart rate monitoring auscultation.
If you need it, the doctor might do a special test called a nonstress test, usually starting around week 32 of your pregnancy. It counts the number of times your baby’s heart speeds up during a 20-minute period.
For the test, you'll lie down with an electronic sensor belt around your belly that continuously records the baby's heartbeat.
The doctor also may wrap an electronic sensor belt around you to measure the baby’s heart rate during labor and delivery. This lets them know if the contractions are stressing your baby. If so, you might have to have your baby as soon as possible.
Internal monitoring: Once your water breaks and your cervix opens to prepare for birth, the doctor can run a wire called an electrode through it and into your womb. The wire attaches to your baby’s head and connects to a monitor. This gives a better reading than listening to your baby’s heartbeat from the outside.
Fetal Heart Rate Monitoring Risks
External monitoring isn’t risky. It doesn’t hurt or use radiation. If your doctor uses a belt, it might be a little uncomfortable. It also might mean you have to stay in bed during labor.
Internal monitoring risks include:
- Slight discomfort
- Bruising or scratching your baby’s scalp
If you’re HIV-positive, you shouldn’t have internal fetal heart rate monitoring. That’s because there’s a risk of passing the infection to your baby. If you have other health conditions, ask your doctor if there are any special risks.
Fetal Heart Rate Monitoring Procedure
Fetal heart rate monitoring could happen in your doctor’s office or at the hospital. The procedure will depend on what type of monitoring you’ll have.
External fetal heart rate monitoring procedure
- Your doctor will ask you to undress and lie down on an exam table or labor bed.
- You’ll get clear gel on your belly.
- Your doctor will press a gadget called Doppler transducer to your belly and move it around.
- You’ll hear the sound of your baby’s heartbeat.
- If your doctor wants to measure the heartbeat continuously, they’ll use a wide belt to hold the transducer in place.
- Your doctor will record the fetal heart rate. You may see it on a computer screen.
Internal fetal heart rate monitoring procedure
- You’ll be asked to undress and lie down.
- You’ll put your feet and legs in supports, like you’re getting a vaginal exam.
- The doctor will check to see if your cervix is dilated.
- If your water hasn’t broken, the doctor may break it.
- The doctor will feel for your baby’s head.
- The doctor will put a thin tube (catheter) with a small wire at the end into your vagina.
- The doctor will put the wire on your baby’s scalp and remove the catheter.
- Once it’s connected to a cable, the wire will record your baby’s heartbeat until a doctor removes it or your baby is born.
Fetal Heart Rate Monitoring Results
A healthy baby’s heart usually beats 110-160 times a minute in the womb. It speeds up when the baby moves. Signs of possible problems include:
- Heart beats slower than 110 beats a minute
- Heart beats faster than 160 beats a minute
- A heartbeat pattern that isn’t normal
- The heartbeat doesn’t go up when the baby moves or during contractions
Lack of a normal heartbeat doesn’t always mean something is wrong with your baby. But it can be a sign that the baby isn’t getting enough oxygen.
Your results also may be less accurate if:
Abnormal Fetal Heart Rate Treatments
If your baby’s heart rate isn't what it should be, the doctor may try:
- Changing your positions to move the baby
- Giving you fluids through an IV
- Having you breathe extra oxygen
- Relaxing your uterus with medicine to slow contractions
- Giving you other drugs
If these steps don’t return your baby’s heart rate to normal, you may need to deliver them right away. If your cervix is completely open, the doctor may use a tool called forceps or a special vacuum to help you push the baby out. Otherwise, you’ll have the baby by cesarean section.