What is Vanishing Twin Syndrome?






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More than likely, unless your family has been known to have twins, you have never heard of the vanishing twin syndrome. For some who may be pregnant with twins, however, this is an important topic to discuss with your doctor and to understand exactly what it is.

1. When was it discovered?

It wasn’t until the mid-1940’s that vanishing twin syndrome even had a name. It exists in women who have been determined to be carrying twins early in their pregnancy only to find that one of the fetuses have disappeared when a later ultrasound is taken. This is the results of a miscarriage of one of the twins. There is no evidence of the miscarriage, however, because the fetal tissue is then absorbed by the remaining twin.


2. How was it discovered?

This phenomenon was only detected before ultrasounds when doctors would examine the placenta after delivery. However, these days, with the advancements of technology, we are now able to see the baby’s heart beat as early as the time that we first find that we are pregnant. Sometimes, when multiple heart beats are detected, one will vanish at a later ultrasound.


3. What are the symptoms?

Some women who experience vanishing twin syndrome may find that they actually experience some of the symptoms that are usually related to having a miscarriage. For these women, a doctor will perform an ultrasound and, most often, will only find one fetus in her uterus. Since it has been given a name, this syndrome has been diagnosed more and more throughout the years, mainly due to the knowledge on the subject. In fact, it is estimated that 21% to 30% of multifetal pregnancies result in vanishing twin syndrome.


4. What causes vanishing twin syndrome? 

One of the biggest questions that women who experience this asks, “how could something like this happen?” Sadly, there is usually no answer to this question and doctors and parents alike are left puzzled. Typically, the surviving fetus has an excellent chance of survival, but its chances rely solely on what caused its twin to die in the first place.

For example, if the miscarriage happened in the second or third trimester rather than the first as is common; there is a greater chance that the surviving twin will miscarry as well. Some babies who are born after their twin miscarries late in pregnancy have been diagnosed with cerebral palsy after birth takes place.


Most women who experience twin syndrome are over the age of 30 and often develop symptoms such as cramps, pelvic pain and bleeding. Although you should seek medical attention if you are experiencing these symptoms, there are no special requirements for caring for the surviving twin if the miscarriage happens early on in the pregnancy.

However, if it occurs during the second or third trimesters, your pregnancy will now be considered high risk and special precautions will need to be made. Your doctor will provide you with strict instructions in order to keep you and your remaining baby safe throughout the remainder of your pregnancy. More than likely, you will need to have close monitoring for the remainder of your pregnancy.


Many times, however, a pregnant woman will not even realize that anything has happened until she visits her doctor for her next ultrasound. She may believe that the first ultrasound was a mistake or that some kind of error has been made. However, chances are this is the outcome of the vanishing twin syndrome.

5. Vanishing twin syndrome and miscarriage

While this syndrome is fairly common among women who are pregnant with multiple babies, it is not something that should be feared as far as a danger to your pregnancy. Just as with any miscarriage, there is really nothing that you can do to prevent the vanishing twin syndrome and there are no treatments necessary if it does occur.


The emotional toll of losing a twin can be somewhat bittersweet and it is important to keep your emotions intact so that your remaining baby is born healthy. If you are experiencing great sadness over the loss of your second fetus, you should consider reaching out to someone that can help you deal with your loss.

Just like with any miscarriage, there are long lasting emotional issues that can surface from vanishing twin syndrome. It is important for family members to be understanding of the feelings of the mother if this does occur and to support her as needed.

What is Vanishing Twin Syndrome?, 5.0 out of 5 based on 1 rating

Dr. Karen Leham, MD

Dr. Karen Leham is double board-certified in Obstetrics and Gynecology and in Reproductive Endocronology and Infertility. Dr. Leham completed her residency at Loyola University, followed by a fellowship at UCLA.