Fetal Heart Rate: What Is Normal and When to Worry

First-time mothers tend to feel anxious when the doctor starts talking about fetal heart rate. What is the normal fetal heart rate and when should a mom be worried?

Fetal Heart Rate

For pregnant women, the best gift is hearing their baby’s heartbeat for the first time. However, there is the moment of anxiety once the doctor or midwife starts mentioning the fetal heart rate. Is the number normal? Is it something to be worried about? Save yourself from these troubling thoughts. Learn more the normal fetal heart rate and how it is measured.

 

Fetal Heart Rate

The fetal heart rate is measured at the time when the baby is at six weeks old. The normal number is between 120 to 160 beats per minute. Take note that the number is twice the number of the normal heartbeat for an adult.

A mother should also understand the fetal heart rate varies and depends on the baby’s gestational age. The heart rate of the baby may start at a slow rate as the heart is still developing. It will increase daily and start to stabilize within the mother’s 12th week.

An average of 120 to 160 beats per minute is noted during the baby’s first hours after birth. However, the amount will change after the first 28 days. The baby’s heart rate rises between 100 to 165 beats per minute when awake, and falls between 90 to 160 beats per minute when asleep.

At one to two months of age, the heart rate of a baby ranges from 100 to 150 beats per minute when awake. It falls between 90 to 160 beats per minute when asleep. Finally, at one year of age, the heart rate falls between 70 to 110 beats per minute when awake, and falls between 80 to 120 beats per minute when asleep.

 

Methods to Monitor Fetal Heart Rate

When it comes to checking a baby’s heart rate, there are three methods.

1. External Monitoring

This is continuous monitoring of the heart rate where sensors are positioned on the mother’s belly. The sensors are attached to a machine which records the heart rate of the baby along with the contractions of the uterus. While this method works for some women, it fails for others. Factors that affect the failure of reading include the mother’s weight, the size of the fetus, or the movement of the fetus.

2. Internal Monitoring

When there are problems with the external monitor, an internal monitor is utilized. This is used in high-risk situations, such as when the amniotic sac has already ruptured, and the mother’s cervix is fully dilated. In this method, an electrode along with a small tube is inserted to the vagina and the cervix. It is then attached to the scalp of the baby. The tube and electrode are connected to a machine where the heart rate of the baby is continuously monitored.

3. Intermittent Auscultation

This involves either a stethoscope or handheld ultrasound device and an electronic monitor to measure the heart rate of the baby. A doctor switches to continuous monitoring only when he or she suspects a problem.

Take note that a woman undergoing labor is continuously monitored whether through external or internal means.

 

Factors That Affect Fetal Heart Rate

As mentioned above, several factors may affect the heart rate of a baby. Such factors include the following.

1. Gestational Age

The heart rate of a baby starts slow, especially in the beginning as the heart is still developing. By the middle of the pregnancy, the heart rate of the baby increases in speed and falls between 120 to 160 beats per minute. If the heart rate of your baby is out of range, then make sure to double check when your baby is due.

2. Fetal Activity

The activity of the baby affects the heart rate, much like adults. When the baby is awake, the heart rate is high. However, if the baby is asleep, then expect that the heart rate is low. A heart rate variability is a good thing as it is one of the markers of good fetal health.

3. Blood Glucose Levels

According to research, a high level of sugar in the blood may directly link to a high fetal heart rate. However, a low level of sugar in the blood contributes to a low fetal heart rate.

4. Mother’s Diet

Chocolate, sugar, and coffee are stimulants that affect the heart rate of the mother. These can also affect the baby’s heart rate. If a mother consumes such food before an ultrasound, then the heart rate of the baby is likely to be high.

 

Using Fetal Heart Rate Monitors at Home

A lot of mothers buy home fetal monitors like a pocket Doppler to listen to their baby’s heartbeat. However, doctors are completely against the use of these home fetal monitors simply because these are not deemed safe for use by the Food and Drug Administration. Other than that, the use of these instruments may lead to cavitation and tissue heating. The use of fetal heart monitors should only be done by trained professionals in a hospital setting.

When to See a Doctor

If the heart rate falls out of the normal range, then it may mean that the baby is in distress. An abnormal heart rate could indicate a miscarriage or a fatal heart condition. However, you should not jump to conclusions. As mentioned, various factors affect the fetal heart rate. Doctors are unlikely to diagnose an abnormal fetal heart rate as a miscarriage immediately. HCG levels are tested, or a follow-up ultrasound is done when the fetal heart rate falls below normal levels.

The only time a mother should seek immediate medical attention is when she experiences a slow heart rate or bradycardia. This is when the heart beat per minute of a mother falls to 60 below. The normal heart rate for pregnant women is 80 to 100 beats per minute.

Maternal bradycardia leads to oxygen deprivation both for the mother and the fetus. Symptoms of bradycardia include shortness of breath, fatigue, weakness, chest pains, and fainting. If you manifest any of the signs mentioned, then head to the hospital at once.

Fetal Heart Rate

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