Vanishing Twins: Causes, Symptoms, Impacts, How To Cope

| Reviewed By Amanda Lundberg, BSN, RN

The probability of complications is higher in twin pregnancies as compared to single pregnancies. To ensure that both babies are born at full term, several factors must align correctly. However, there are cases where this does not happen and there is a risk of losing one or both babies.

What is vanishing twin syndrome (VTS)? Vanishing twin syndrome occurs when there is a miscarriage in a twin pregnancy. One baby doesn’t make it, and the twin who was miscarried is considered the vanishing twin. The pregnancy becomes a singleton pregnancy, and the physical and emotional impact on the parents can be devastating.

Knowing what you can about vanishing twin syndrome can help you overcome the loss. The symptoms and treatment for this condition vary, and there’s a lot we still don’t know about it.

How Common Is Vanishing Twin Syndrome?

It’s not easy to know exactly how common vanishing twin syndrome is because a miscarriage can occur before the mom even knows she is pregnant with twins. Situations where this occurs make it impossible to accurately track VTS. 

If you look at the statistics we have based on ultrasounds because a woman had IVF, the number is anywhere between 7 and 36 percent. However, this only factors in IVF pregnancies and not spontaneous twin pregnancies.

When Does Vanishing Twin Occur?

Vanishing twin syndrome can occur throughout the pregnancy, but it often happens before the first ultrasound. In these situations, you may not even know you were pregnant with twins unless you happened to go in for a very early ultrasound.

You can experience VTS later in pregnancy. In the second and third trimesters, it’s a more dangerous situation that will have to be monitored and managed with care.

Can You Miscarry One Twin at 6 Weeks? 5 Weeks?

You can miscarry a twin at five or six weeks of pregnancy, but it’s unlikely you will know. In fact, you may not even know you are pregnant at all when you experience VTS.

Some women don’t have regular periods and may not know they’ve missed one. 

Even if you know you’re pregnant, most doctors won’t have you come in for an ultrasound until later in the first trimester. If you miscarry a twin as early as five or six weeks, you likely won’t be aware of it.

Vanishing Twin Syndrome After Heartbeat

A heartbeat can be detected fairly early in a pregnancy, sometimes around five or six weeks. If two heartbeats are heard, that’s a sign that you are having twins.

If VTS occurs after a heartbeat has already been detected in both twins, then only one heartbeat will remain. However, you may not have an appointment to check for the heartbeat until later in the first trimester.

Again, you could miscarry a twin without knowing you were even pregnant with twins.

What Causes Vanishing Twin Syndrome?

Vanishing twin syndrome occurs when one twin’s DNA has irregularities that prevent it from growing and developing the way it’s supposed to in order to survive. This is outside of anyone’s control. 

Vanishing Twin Syndrome Symptoms

Any of the following symptoms could be a sign that you’re experiencing VTS, so seek medical help if you have them.

  • Bleeding, even if it’s just spotting
  • Pain in the back or pelvis
  • Uterine cramps

What Are HCG Levels Like in Vanishing Twin Syndrome?

Human chorionic gonadotropin levels, also known as HCG levels, are an important indicator in any pregnancy.

They show that your body is supporting a fetus, and in the case of twins, HCG levels are higher because you are supporting more than one fetus.

If your HCG levels drop during a twin pregnancy, that is a sign that you could be experiencing VTS. However, it’s not the only way to diagnose and should be followed up with other tests.

Do You Bleed if You Miscarry One Twin?

It is possible to experience light bleeding if you miscarry one twin, but you might not. In fact, if you lose a twin early in the pregnancy, you may not even know. Your body and the surviving twin would absorb the tissue of the twin who was miscarried.

How Long Do You Bleed With A Vanishing Twin?

How long you bleed after a miscarriage depends on different factors. Some women lose a twin early in the pregnancy, and they may only bleed lightly for a matter of hours.

Other women may bleed for weeks and pass clots during this time. See your doctor if you experience any bleeding or spotting during your pregnancy.

What Happens When One Twin Dies in the First Trimester?

When one twin dies in the first trimester, the tissue of the fetus is absorbed by the remaining fetus and the mom. This is not a dangerous process for either of them.

In fact, you may not even know you’ve had a miscarriage, and if you didn’t already have an ultrasound, you may not be aware that you were ever pregnant with twins.

What Happens When One Twin Dies in Utero at 20 Weeks?

If one twin dies during the first trimester, the outlook for mom and the other twin is still very good. However, if one twin dies in the second or third trimester, things get more complicated.

After 20 weeks, one twin dying in the womb can put their sibling at risk. 

If the twins shared a placenta, then the living twin will be closely monitored to make sure growth is still occurring. No matter the situation, the pregnancy will remain high risk, and doctors will monitor it closely until both twins exit the womb.

Removing a Dead Twin

Sometimes it’s necessary to remove the twin who passed instead of carrying him to term. Before this happens, doctors may give mom steroids to help the remaining twin’s lungs develop and give him the best chance for survival.

It’s unlikely that a dead twin will be removed from the womb if it can be avoided since it presents risks to the living twin and to mom.

Carrying a Dead Twin Fetus To Term

While carrying a dead fetus to term may sound devastating, it’s often the safest option for the pregnancy. This gives the living twin time to continue growing. 

Doctors may choose to deliver the living twin early if the twin fetus has passed and the living twin is developed enough for survival outside of the womb.

Vanishing Twin Impact on Surviving Twin

If a twin dies during the first trimester, there will likely be no impact on the surviving twin. If it happens later, doctors will monitor you closely to make sure your living twin is getting the nourishment he needs from the placenta. 

There was a belief in the past that a surviving twin might be at increased risk for cerebral palsy, but further studies showed that more research needed to occur before that conclusion could be drawn.

Surviving Twin Syndrome

The surviving twin will likely not be emotionally impacted by the death of their twin in utero, though no one can say for sure.

Twins begin interacting with each other as early as 14 weeks gestation. That means a loss after that would likely not go unnoticed by the living twin. However, there’s no evidence to show that the living twin will be affected.

Vanishing Twin Reappearing

Vanishing twins cannot reappear. With all the tools doctors have to diagnose VTS today, not being able to find a baby in the womb and then being able to find them again is not likely at all.

However, you can be misdiagnosed with VTS if the proper tests aren’t performed. If only HCG levels or a doppler to check heartbeat were used, then there is a chance of an inaccurate diagnosis.

An ultrasound should be performed. If that shows that one twin has vanished, then he or she is gone.

Chances of Vanishing Twin Reappearing

Once you miscarry, there is no chance of the baby reappearing. Unless you were given the wrong diagnosis to begin with, a VTS diagnosis is irreversible.

How To Know if You’ve Had a Vanishing Twin

In many cases, you won’t know you’ve experienced VTS. If it happens early enough in the pregnancy, you may not have any idea you were ever carrying two babies.

If you miscarry one twin later in the pregnancy, you will likely have the symptoms of a miscarriage. An ultrasound will show that there is only one baby where there used to be two.

How To Cope With Vanishing Twin Syndrome

If you’ve experienced VTS, it’s important to get the support you need.

Besides seeing your doctor to make sure all of your physical needs are taken care of, you should also seek out emotional support from family, friends, or a VTS support group.

It’s normal to mourn this loss, and you don’t have to walk through the grief alone.

Final Thoughts

Vanishing twin syndrome can occur without you even knowing. However, when you are aware that one twin has been lost, it can be a devastating experience.

Know that there was nothing you could have done to stop it, and reach out to get the help you need to heal.