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What Is A Normal Fetal Heart Rate

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Nonstress Test And Cardiotocography

READING AND INTERPRETING A FETAL HEART RATE MONITOR

Fetal heart rate characteristics are normally controlled through parasympathetic innervation, in which the vagus nerve innervates both the sinoatrial and atrioventricular nodes. This tonic influence results in decreased rates of firing, thereby controlling the FHR. The vagus nerve also transmits impulses that result in FHR variability. When a fetus is exposed to prolonged periods of uteroplacental insufficiency, a noradrenergic response through the fetal adrenals occurs. This supersedes vagal influence, leading to both fetal tachycardia and decreased variability. If this continues, there is ultimately myocardial depression that manifests as late decelerations. Thus, in theory, instituting nonstress tests should identify fetuses at risk for adverse perinatal outcome. This is supported by observational studies demonstrating lower stillbirths in pregnancies with reactive NSTs than in those with nonreactive NSTs in addition to a lower stillbirth rate when NSTs are increased from once to twice per week.160,161

Andrew D. Hull, Thomas R. Moore, in, 2005

Why Might I Need Fetal Heart Monitoring

Fetal heart rate monitoring is especially helpful if you have a high-riskpregnancy. Your pregnancy is high risk if you have diabetes or high bloodpressure. It is also high risk if your baby is not developing or growing asit should.

Fetal heart rate monitoring may be used to check how preterm labormedicines are affecting your baby. These are medicines are used to helpkeep labor from starting too early.

Fetal heart rate monitoring may be used in other tests, including:

  • Nonstress test. This measures the fetal heart rate as your baby moves.
  • Contraction stress test. This measures fetal heart rate along with uterine contractions. Contractions are started with medicine or other methods.
  • A biophysical profile. This test combines a nonstress test with ultrasound.

Things that may affect the fetal heart rate during labor:

  • Uterine contractions
  • Pushing during the second stage of labor

Your healthcare provider may have other reasons to use fetal heart ratemonitoring.

What Kind Of Monitoring Do I Need

Auscultation is generally considered an acceptable form of monitoring if:

  • Your pregnancy is low-risk.
  • You havent had complications during labor.

You will need continuous monitoring if:

  • You have a high-risk pregnancy.
  • Complications develop during labor.
  • You have an epidural for pain.
  • You have to have medicine to induce or speed up labor.

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What Treatments Are Available

In most cases we can reduce the fast heart rate by giving medication to the mother, which passes through the placenta to the baby.

We perform a simple test on the mothers heart called an electrocardiogram before prescribing the medication. Some stickers will be applied to the chest to check your heart rhythm and that it is safe to give you the medication. Some medications can take two to three weeks before they are effective in reducing a babys heart rate.

Usually treatment is given as an outpatient and does not need a stay in hospital. However, we will monitor you and your babys heart rate regularly when you first start taking it. The aim of treatment is to control the rhythm of the babys heart, which in most cases allows a normal birth at term . We may need to take blood samples from you to check the levels of the medication in your body to make sure that they are within the correct range.

Occasionally, we may have to try more than one medication before we are able to reduce the babys tachycardia. The type of treatment selected depends on a number of factors including the type of the tachycardia, how many weeks pregnant you are, and if there are signs of hydrops. We may need to reassess treatment if medication is not effective in reducing your babys heart rate.

When Can You Hear Your Baby’s Heart Beat

Normal Fetal Heart rate chart by weeks. You

Your pregnancy has three parts or trimesters. It means the journey of your baby from week 1 to week 42 has three stages. So many factors can affect when you can hear your baby’s heartbeats. Your body weight, position of your baby, and the placenta’s location can all come into play. It is usually possible around 18-20 weeks in most cases, but sometimes, you can hear it at about week 12- this is with the help of a fetoscope or stethoscope. With ultrasound, it is possible to hear your baby’s heartbeats at 8 weeks. You do not need to worry though if you cannot hear fetal heart tone at 12-14 weeks of pregnancy.

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What Can Fetal Heart Rate Monitoring Tell Us About Your Babys Heartbeat During Labor

If youre between 38-42 weeks in your pregnancy and youve gone into labor, your medical team will immediately set up fetal heart rate monitoring to first asses your babys heartbeat and health during birth. The main purpose of fetal heart rate monitoring is to provide information by observing your baby s heartbeat and alerting your doctor if your baby may not be getting enough oxygen or blood flow. We want to see your healthy baby come through pregnancy, labor and delivery as smoothly as possible. We dont want the stress of labor to threaten a baby s heart, health or development, which is why a monitoring system as early as possible is so essential.

A baby s heart rate during labor should be between 110 and 170 bpm depending on which week youve gone into labor, but it may fluctuate above or below this rate for a variety of reasons. Short bursts of acceleration of the babys heart rate are usually common and indicate that the baby is getting an adequate oxygen supply. We know that brief decelerations in the baby s heart rate are also normal and do not indicate poor fetal health. Accurate results are based on the use of a monitoring system reviewed by your health care team, regardless of how many weeks of gestation your baby is.

Is It Safe To Monitor The Babys Heart Rate At Home

Home fetal heart rate monitors work by using very low emission ultrasound technology, and should be used only after your doctors approval. Also, frequent use of ultrasound can lead to tissue heating and formation of small bubbles in some tissues. The long-term effects of tissue heating and cavitation on the mother or the child are unknown .

Use of fetal rate monitors at home is recommended only after 10 to 12 weeks of pregnancy. The results you get should not be considered final or not override the results of the scan by the medical professional .

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Faq: Is 140 A Normal Fetal Heart Rate

A normal fetal heart rate usually ranges from 120 to 160 beats per minute in the in utero period. It is measurable sonographically from around 6 weeks and the normal range varies during gestation, increasing to around 170 bpm at 10 weeks and decreasing from then to around 130 bpm at term.

What Is A False

Maternal Newborn (OB) Nursing – Fetal Assessment and Fetal Heart Rate Patterns

False-positive fetal heart rate monitoring readings which may indicate there is a problem when the baby is actually fine are common.Your doctor has a range to classify your babys prenatal development and fetal heart rate readings during pregnancy. The range is reviewed according to three categories:

  • Category One: Everything is normal and no action or test is needed.
  • Category Two: Readings are unclear and may be further reviewed, or require more internal information such as an additional test, evaluation and surveillance.
  • Category Three: Readings around the heart rate are abnormal and may require prompt evaluation and action.

Medical professionals can see fairly early on when a baby s heart looks normal and healthy and know when something is wrong during gestation and we need to take immediate action . In the middle, it may get complicated, and this range is where false-positives often show up based on what your doctor can and cant see through external ultrasound monitoring. A lot of factors go into assessing if a baby is healthy during birth for example, the mothers pregnancy health from the first trimester affects the baby, and must be reviewed as early as possible. This is where the use of one device cant replace the care of a good doctor. The results are usually related to the context of whats going on around gestation during any given week, and we know an internal fetal heart rate device cant give us this information.

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What Fetal Heart Rate Monitoring Can And Cant Tell Us

    Electronic fetal heart rate monitoring keeps track of your babys heart rate and helps determine the strength and duration of your contractions. Listening to your babys heart rate is one way we can tell how he or she is doing on their way to meet the world.

    While fetal heart rate monitoring can alert us to potential problems, its also important to remember that a variety of factors, not just heart rate, help us determine how well your baby is doing. Fetal heart rate monitoring is not a crystal ball that predicts your babys future health.

    I know this from experience. My sons fetal heart rate looked terrible toward the end of delivery, which led to a few scary moments. However, he perked up shortly after birth and was just fine.

    Ultrasound And Congenital Heart Defects

    Your first prenatal ultrasound, which is scheduled sometime between the 6th and 9th week, confirms your pregnancy, determines due date and monitors the heartbeat. Considering that nearly 1% of births every year are known to have congenital heart defects, the doctor observes the structure of the heart to check for any congenital disabilities in the second ultrasound, or the 20th-week anatomy scan .

    Though there is no treatment in utero, it helps the doctors decide when and how to deliver the baby. Most congenital issues are corrected after the babys birth, either through surgery or medications. If there is a problem with the fetus heart rhythm, your doctor may suggest medications to decrease the risk of complications in the baby.

    If you are anxious to listen to your babys heartbeat, check with your doctor about it. If there are any concerns with the heart rate, it will be monitored closely through the pregnancy. But if you want to monitor it at home, talk to your doctor first.

    How did you feel when you heard your babys heartbeat for the first time? Share with us in the below comment section.

    References:

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    Ten Steps In Imaging Heart

    1st Step: Check the heart is beating. M-mode heart rate should be between 120 and 180 beats per minute

    2nd Step: Situs- check which is the left side of fetus then do a dual image in a tranverse axial plane of the fetus with firstly the thorax showing the heart apex orientated to the left at an angle of approximately 45degrees. The transverse section should only contain 1 rib. The second image showing the stomach on the left ensuring the left and right side is labelled.

    3rd Step: Four Chamber View- Angling cephalad from a transverse axial view of the abdomen.

    The heart should occupy approximately 1/3 of the chest.The ventricles should be of similar size and the atria should be of similar size. The moderator band is in the right ventricle. The left ventricle extends more apically.Assess the AV valves ie The tricuspid valve on the right is more apical than the mitral valve insertion onto the interventricular septum. Watch ,in real time, the opening and closing of the valves in systole and diastole.The pulmonary venous connections can be identified.

    6th Step: 3 Vessel View This view is a slightly oblique, axial view.

    It cuts the upper part of the arches and transversally the Superior Vena Cava.

    7th Step : Arrowhead

    The pulmonary artery and the transverse aorta will merge posteriorly and should be an acute angle not curved/rounded.

    9th Step: Aortic Arch

    The arches are best assessed when the foetus is prone.

    10th Step: Ductal Arch

    References

    Prenatal Ultrasound Showing Fetal Tachycardia

    Table 4 from What is the ânormalâ? fetal heart rate ...

    This information sheet from Great Ormond Street Hospital explains about fetal tachycardia detected during a prenatal ultrasound scan and what this might mean for your child. It will support the information discussed with you by your doctor and nurse at your appointment and it is important to remember that every case is slightly different.Tachycardia is an abnormally fast heart rate. The normal fetal heart rate is between 120 and 160 beats per minute. Typically, an abnormally fast heart rate is over 200 beats per minute.

    The heart is made up of four chambers two at the top called atria and two at the bottom called ventricles. The ventricles are the pumping chambers of the heart. It is the top two chambers of the heart that set the pace of the heart, and normally the ventricles only respond to electrical impulses from the atria.

    In some fetuses, the atria and ventricles are both beating fast but at the same rate . In others, the atria beat exceedingly fast , much faster than the ventricles . Other rhythm disturbances may occur but are much rarer.

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    Why Texas Childrens Fetal Center

    • A single location for expert maternal, fetal and pediatric care. At Texas Childrens Hospital, mothers and babies receive the specialized care required for the diagnosis and treatment of congenital heart conditions all in one location, for highly coordinated care and treatment planning.
    • A skilled, experienced team with proven outcomes. We have a dedicated team of maternal-fetal medicine specialists, fetal imaging experts, cardiologists, neonatologists, electrophysiologists and others who work in concert to care for you and your baby every step of the way, using proven protocols weve developed over the years. With their combined expertise and unified approach, this team offers the best possible care for pregnancies involving fetal arrhythmias.
    • We care for your childs needs at every stage of life. Our comprehensive approach starts with your first prenatal visit and continues through delivery, postnatal care, childhood and beyond, as needed, thanks to one of the nations leading teams of fetal and pediatric heart specialists.

    Additional Information And Declarations

    Competing Interests

    Nadja Harner was an employee of Trium, Anne-Laure Boulesteix was an employee of the SLC when the study was conducted.

    There is no known financial or other conflict of interests for the other authors.

    conceived and designed the experiments, performed the experiments, analyzed the data, wrote the paper.

    and conceived and designed the experiments, analyzed the data, contributed reagents/materials/analysis tools, wrote the paper.

    analyzed the data, contributed reagents/materials/analysis tools, critical review of manucript.

    analyzed the data, contributed reagents/materials/analysis tools.

    performed the experiments, analyzed the data, wrote the paper.

    performed the experiments, and critical review of mansucript.

    conceived and designed the experiments, performed the experiments, and critical review of manuscript.

    Human Ethics

    The following information was supplied relating to ethical approvals :

    The work program and the corresponding contracts were approved by the Department of Obstetrics and Gynecology of the Technische Universität München and the legal department of the Technische Universität München, and by the Ludwig Maximilians University .

    Patent Disclosures

    The following patent dependencies were disclosed by the authors:

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    What Does It Mean If Your Babys Heart Rate Is High

    If the heart beats too fast, contractions are shallow and not enough blood is pumped with each heartbeat. As a result, the fetus can go into heart failure. The most common form of this condition is called supraventricular tachycardia , in which the heart rate can be faster than 200 beats per minute.

    When Can You Hear Your Babys Heartbeat With Doppler

    Measuring Fetal Heart Rate with M-Mode

    You’ll most likely hear your babys heartbeat with a Doppler at around the 12 week mark, but you may hear it as early as week 10. Your doctor or midwife will place this handheld ultrasound device on your belly to amplify the pitter-patter of the heart.

    Keep in mind that experts including the Food and Drug Administration warn against using at-home fetal Dopplers unless youre under the supervision of a medical professional.

    Thats in part because these devices arent as sophisticated as the ones that doctors use, so they may not pick up on a babys heartbeat leading to an unnecessary scare. Plus, it can be hard to use an at-home Doppler properly without training. You could, for example, mistake your own heartbeat for your babys.

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    What Happens If Baby Isnt Coping

    The main reason why care providers monitor babys heart rate during labour is to detect signs of fetal distress, which usually relate to babys supply of oxygen being compromised in some way. If this is detected early, care providers can intervene and potentially prevent complications such as cerebral palsy, seizures and death.

    One complication is that there is no consensus on exactly how fetal distress is defined. Different care providers have their own definitions, depending on their professional experience, and they react to changes in fetal heart rates accordingly.

    If your care provider picks up variations in your babys heart rate, it can be very frightening to hear there might be a problem with your babys wellbeing. Your doctor or midwife might decide to take a tiny sample of blood from your babys head, for testing. The oxygen levels in the blood sample will indicate how your baby is coping.

    If possible, your care provider will try to ease your babys distress by:

    • Ensuring you are well hydrated, which could mean giving fluids via IV.
    • Having you change positions especially if you have been reclining on your back, which puts the weight of the uterus on a major vein in your body.
    • Making sure you have adequate oxygen levels.

    If these changes dont improve your babys heart rate, your care provider will advise that your baby should be born as quickly as possible. How your baby is born will depend on the stage of labour you are in, and how dilated your cervix is.

    Can You Determine Gender Through The Babys Heart

    No, the heart rate cannot predict the sex of your baby. There are lots of old wives tales surrounding pregnancy. You may have heard that your babys heart rate can predict their sex as early as the first trimester. If its over 140 bpm, youre having a baby girl. This is typically not valid form of gender determination. It is fun but it does not tell you the gender. You can always guess and perhaps 50% of the time you will be correct since there are only two genders to choose from. We at Pregnancy Treasures are accurate with gender determination if you are 14 weeks into your pregnancy we can tell you via ultrasound. Call or go online for details

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