As you labor to bring your baby into the world, your care team works to keep you and your baby as safe and healthy as possible. One tool your care team relies on is called a fetal heart rate monitor.
Knowing more about this important piece of monitoring equipment and what it does can empower and comfort you as a laboring mother. When you feel more familiar with this technology, you won't become unnecessarily alarmed by its flickers or beeps.
What Is Fetal Heart Rate Monitoring?
Think of fetal heart rate monitoring as an early warning system. By monitoring your baby's heart rate and rhythm during labor, your care team can often be alerted to problems early enough to intervene and address them.
Typically, your baby's heart beats steadily between 110 and 160 times per minute. But if your baby feels stressed by conditions in the uterus, lacks enough oxygen or blood flow, or develops an infection, its heart will start to beat faster (accelerations), slower (decelerations), or more irregularly (arrhythmias).
These changing heart rate patterns can provide invaluable data and insights that might direct further action. For instance, they can indicate the following:
- You may need to receive oxygen or IV fluids.
- Your baby is in distress and needs to come out immediately.
- Your labor is continuing normally.
Are There Different Types of Fetal Heart Rate Monitors?
Several types of fetal heart rate monitors are available and widely used—each with its own risks and benefits, as well as different levels of invasiveness and data collection.
Intermittent Auscultation
With this method, your caregiver will use ultrasound Doppler—a handheld wand and some gel on your belly—to check your baby's heart rate and rhythm at regular intervals. This method is best for low-risk labor. It is free of wires or straps, lets you move freely, and can be used in different positions—even underwater.
One risk is that this method, like many others, can sometimes pick up your heart rate instead of the baby's, causing confusion. Its intermittent use means that issues may not be detected as quickly.
Electronic Fetal Monitor
With this method, your caregiver will strap two tools, called transducers, to your belly and secure them with belts:
- An ultrasound transducer to monitor the baby's heart rate
- An external tocodynamometer with a pressure transducer to measure your contractions
These are generally kept on continuously and restrict your mobility, as they are connected by wires to heavy equipment that prints out data for your care team. While this method is bulky and limits movement, it provides consistent, detailed data about how you and your baby are doing.
Wireless Fetal Monitor
A new method now available is a wireless version of the electronic fetal monitor. This uses similar transducers attached to your belly, but does not require you to be plugged into any equipment; the heart rate readings are transmitted wirelessly to a central device. GE HealthCare's Novii™ Wireless Patch system uses a patch and a small "pod" containing a battery.
This method has the clear advantage of providing continuous data without restricting movement during labor. It is also waterproof, allowing for bathing during labor. However, it may not always pick up data as well as plugged-in versions do, and some facilities do not yet carry this technology.
Internal Fetal Monitor
This method may not need to be used but is helpful if your care team becomes worried about how your baby is doing. A fetal scalp electrode (FSE) is placed to monitor the baby's heart rate more closely, and a device called an intrauterine pressure catheter is placed in the uterus through your cervix to measure the exact pressure and strength of your contractions.
Together, these tools give more accurate, detailed data, but they do carry some risk of infection. The electrode can also cause a small cut on the baby's scalp, but it usually heals without complications or scarring.
How Is a Monitoring System Selected?
One of the key factors in deciding what kind of fetal heart rate monitor will help keep you and your baby the safest is the level of risk in your particular labor and delivery situation.
Many women are considered low risk for labor complications; therefore, the American College of Obstetricians and Gynecologists and the American College of Nurse-Midwives recommend the use of intermittent auscultation to monitor the baby's heart rate.1,2 Research published by The Cochrane Pregnancy and Childbirth Group supports this recommendation, showing that intermittent auscultation can keep you both safe while reducing the chances of unneeded interventions, such as C-sections.3
However, if you have conditions such as, but not limited to, preeclampsia, diabetes, a prior C-section, preterm labor, intrauterine fetal growth restriction, or meconium-stained amniotic fluid, based on evidence-based research and practice your care team will want to keep a closer eye on you and your baby.
Ask your care team about your risk profile and discuss the details of what type of fetal heart rate monitor will be best. Remember that labor is a dynamic process, and although you may be low-risk at the beginning of labor, if your care team notices changes in you or the baby's condition, you may need more continuous monitoring. Keep asking questions as labor progresses so you know what level of monitoring is right for the moment.
What's Best for Your Delivery?
Michelle Dowell, a GE HealthCare engineer and mother of two children under age three, had the unique experience of using tools she helped design during her labors. With her first child, a traditional external fetal monitor was used.
"When you are directly connected to the big monitor, you can't really move too far away from it," she reflected. Knowing the advancements in fetal monitoring technology, Michelle advocated for a different option with her second child. "The second time, I asked for the Novii Wireless Patch system," she said. "You're not tethered to the big monitor the whole time."
Know that newer monitoring options such as wireless fetal heart rate monitors can give the continuous, detailed data of traditional electronic fetal monitors with the ease and independence of intermittent auscultation. And know that you can ask for that newer option if it is appropriate.
Fetal heart rate monitors are one tool to keep you and your baby safe and healthy. Talk with your care team before and during your delivery to find the best balance between safety and comfort. The marriage between technology and open communication will ensure you both get through labor and delivery as smoothly and safely as possible.
References:
- Bryant AS, Borders AE. Approaches to limit intervention during labor and birth. The American College of Obstetricians and Gynecologists Clinical Committee Opinion. February 2019;133(2). https://www.acog.org/clinical/clinical-guidance/committee-opinion/articles/2019/02/approaches-to-limit-intervention-during-labor-and-birth
- Intermittent auscultation for intrapartum fetal heart rate surveillance: American College of Nurse-Midwives. Journal of Midwifery & Women's Health. 2015;60(5):626-632. doi:10.1111/jmwh.12372
- Alfirevic Z, Devane D, Gyte GM, et al. Continuous cardiotocography (CTG) as a form of electronic fetal monitoring (EFM) for fetal assessment during labour. Cochrane Database of Systematic Reviews. 2017;2(2). doi:10.1002/14651858.cd006066.pub3
