Can Fetal Heartbeat Disappear and Reappear? 4 Explanations

| Reviewed By Amanda Lundberg, BSN, RN

The beating of a baby’s heart brings comfort and reassurance to an expectant mother.

The days leading up to the next ultrasound can be full of anticipation as she waits to hear that precious sound that confirms her baby is doing well. 

Unfortunately, ultrasounds can cause a lot of anxiety and heartbreak when they do not show what a mother is expecting to hear.

“I can’t find the heartbeat” are the most unwanted words to hear from an ultrasound technician and can leave a mother heartbroken, confused, and wondering if there is some mistake. 

Once a heartbeat has stopped, it does not reappear. However, an error could occur wherein the heartbeat is missed but later detected again. This does not mean that the heartbeat has stopped and restarted but that the issues preventing the heartbeat from being detected have been resolved.

Let’s dig a little deeper and look at why a fetal heartbeat can stop and what this could mean for the baby and the expecting mother. 

Causes of Fetal Heartbeat Disappearing and Reappearing

Detecting a fetal heartbeat is not always an easy and seamless process. Sometimes there are factors that affect the ability of the doppler to pick up the heartbeat, especially if the embryo is still very small.

This can make it seem like the heartbeat is disappearing and reappearing when, in reality, there are external factors working against the ultrasound technology making it difficult to pick up the heartbeat consistently. 

Baby Is Not in Ideal Position

The uterus can be like a pool for your little baby, and they have lots of space to move around freely while they are inside of it, especially early on in pregnancy.

Unfortunately, a doppler does not allow its user to see inside your uterus in order to find your baby. It is possible that your baby may have moved into an awkward position that the doppler cannot find. 

Tilted Uterus

It is possible for a woman to have a tilted uterus. In this case, instead of tilting forward toward her abdomen, her uterus tilts backward and curves toward her spine.

About 25% of women have a tilted uterus. While a tilted uterus will have no negative impact on pregnancy or delivery, it could make finding the baby’s heartbeat more difficult. 

Anterior Placenta

Sometimes the placenta can grow toward the front of the uterus instead of toward the back.

This is very common and is not usually a cause for concern during pregnancy, but it can make it difficult for the doppler to pick up the baby’s heartbeat.

The doppler will pick up your blood flow rather than the baby’s. Fortunately, this should not be an issue past 10 weeks of your pregnancy as your little one’s heartbeat should be stronger and easier to detect. 

Mother Is Overweight

If you are plus-sized or overweight, there is more tissue between the ultrasound transducer and your baby. This can make it challenging for the sonographer to find the heartbeat. In these cases, a transvaginal ultrasound would be a better option. 

Can a Fetal Heartbeat Stop and Start Again?

Once a fetal heartbeat stops, it cannot restart. However, many women are given the bad news in error and later rediscover that the heartbeat was there all along.

These instances usually occur early on in the pregnancy when the embryo is very small and detecting the heartbeat is more difficult. 

Why Fetal Heartbeat Stops – 7 Main Causes

Unfortunately, there are cases when a baby’s heartbeat truly stops. This is an indication of a more serious problem and leads to pregnancy loss. 

1. Abnormal Chromosomes

Your egg or the father’s sperm may have carried an unusual chromosome. Chromosomal abnormalities are responsible for between 50 and 60 percent of miscarriages.

These abnormalities prevent a baby from developing correctly and often result in a miscarriage. Chromosomal abnormalities are most often caused by a random glitch in the cell division.

There may be a genetic factor, and testing is available if you would like to pursue further investigation. 

2. Twisted Umbilical Cord

Occasionally, the umbilical cord could get twisted, knotted, or compressed. This results in issues with the baby’s blood supply and most often results in pregnancy loss if it happens in the womb or in early pregnancy when delivery is not possible. 

3. Low Progesterone

Progesterone is the hormone required to sustain early pregnancy. It helps with the growth of both the uterus and the fetus. 

If this hormone level drops too low, a spontaneous miscarriage can occur. If this happens to you once, fortunately, it is possible to take supplemental progesterone to prevent it from happening again. 

4. Infections

Infections in the mother’s body can be extremely dangerous during pregnancy.

If left untreated for an extended period of time, infections like rubella, cytomegalovirus, bacterial vaginosis, and several sexually transmitted infections (STIs) can result in a miscarriage. 

5. Blood Supply Issues

Blood clotting in the placenta or along the umbilical cord, high blood pressure, diabetes, and developmental issues with the placenta can result in a drop in the oxygen levels transferred from mother to baby.

When these levels drop too low, a baby’s heart will stop beating. 

6. Chronic Health Conditions in Mother

Sometimes a mother’s body is simply not in the condition to sustain a pregnancy.

Certain conditions such as high blood pressure, uncontrolled diabetes, infections, thyroid disease, and uterus or cervix problems can cause serious complications in pregnancy. 

7. Injuries

Any sudden trauma sustained by a pregnant woman can put her at risk of experiencing a miscarriage.

The body is designed to protect the fetus, however, forceful impacts caused by falls or accidents could cause complications that may lead to a miscarriage. 

No Fetal Heartbeat but No Signs of Miscarriage

It is possible for a baby to have no heartbeat and for the mother not to miscarry right away. This is known as a silent miscarriage or missed abortion.

This is a pregnancy loss in which the embryo has died but the body does not expel it right away. When this happens, nothing wrong is found until weeks after the baby has passed away. 

The mother often has no idea she has miscarried because she does not experience any of the symptoms that accompany a pregnancy loss, like cramping or bleeding.

Instead, she will find out at her next ultrasound when a heartbeat cannot be detected. 

Once a doctor has declared a missed miscarriage (usually after a few ultrasounds to confirm lack of fetal heartbeat), the mother will have a few different options for what to do next.

If she is still early in her pregnancy, she may opt to let her body miscarry naturally or with the help of medicine. If she is further along, her doctor may recommend a dilation and curettage (D&C), a surgical procedure to remove the fetus. 

Can an Ultrasound Be Wrong About No Heartbeat?

While ultrasounds are definitely the most reliable way to detect a fetal heartbeat, errors are possible. These errors could be human errors or could be caused by the movement of the baby, the precision of the equipment, etc.

It is important to always ask for a second opinion when an ultrasound cannot detect a heartbeat. 

What Happens if Fetal Heartbeat Stops

If a fetal heartbeat is not detected on an ultrasound, the technician or doctor will likely try a few different things before declaring a miscarriage.

This is especially true if you are early on in the pregnancy and detecting a heartbeat can be interrupted by the baby’s position, movement, etc.

Often, a transvaginal ultrasound will be done to try and detect a heartbeat. If you are further along in your pregnancy and a heartbeat cannot be detected, a miscarriage is more likely as the heartbeat should be easier to find and not more difficult.

However, it is recommended to get a second opinion before declaring it a miscarriage, especially if there are no other accompanying signs. 

If there is no fetal heartbeat and a doctor has declared a definite miscarriage, the next step will be to remove the embryo or fetus from the body. This can be done by allowing the body to pass the tissue naturally or by surgically removing the tissue. 

Closing Thoughts

Ultrasounds can be the most comforting part of pregnancy, but they can also cause the greatest emotional roller coasters.

We hope this article provided you with some answers, explanations, and a greater understanding as to why fetal heartbeats can stop and why, sometimes, they seem to reappear.