Early ultrasounds offer several advantages, as they allow you and your doctor to identify multiple pregnancies promptly, leading to better care for both you and your babies. Additionally, early ultrasounds can uncover losses, such as the miscarriage of a twin or triplet, which might have remained undetected in the past. This occurrence is referred to as vanishing twin syndrome.

What Is Vanishing Twin Syndrome?

Vanishing twin syndrome is a condition that can occur during early or later pregnancy, where one of the embryos or fetuses in the uterus stops developing and is absorbed by the surviving baby and its mother. Diagnosis can lead to feelings of confusion, anxiety, and grief for individuals who were initially told they were carrying multiple pregnancies.

Historical statistics on vanishing twin syndrome are limited due to the introduction of ultrasound technology in the 1940s, which has shed light on its prevalence and now allows for more frequent diagnosis. In some cases, a vanishing twin can occur before the first ultrasound appointment at 12 weeks, making it undetectable to parents and doctors. Some research indicates that a vanishing twin may be more common after natural conception of twins compared to in vitro fertilization, with an estimated occurrence of 18.2%. Other estimates suggest the occurrence rate could be as high as 30% in pregnancies with multiples. (It's important to note that losing a developing fetus during the latter part of pregnancy is considered a late-term miscarriage, with causes and statistics varying widely.)

What Are Vanishing Twin Syndrome Symptoms?

While some pregnancy symptoms may raise the possibility of vanishing twin syndrome, it's important to remember that these symptoms are not definitive indicators of the condition. Pregnancy experiences vary for each individual, and fluctuating or "disappearing" symptoms are generally not a cause for concern.

Potential signs of vanishing twin syndrome may include cramping and bleeding, which could indicate that one of the embryos has stopped developing. Additionally, abnormal hCG levels, particularly a plateauing pattern after an initial high, may suggest the possibility of one fetus no longer progressing in the pregnancy. However, it's essential to consult with a healthcare professional for proper evaluation and diagnosis.

What Causes Vanishing Twin Syndrome?

Vanishing twin syndrome is not influenced by the pregnant individual's lifestyle choices. Research indicates that there are more cases in women over the age of 30. Like most early miscarriages, it often seems to occur due to chromosomal abnormalities. When an embryo implants and begins development, DNA replication may result in chromosomes being switched or missing, leading to a nonviable fetus. In pregnancies with twins or multiples, each set of DNA develops independently, allowing one fetus to continue growing while its twin stops developing. Improper cord implantation may also be a cause.

How is Vanishing Twin Syndrome Diagnosed and Treated?

Vanishing twin syndrome is often detected during an ultrasound appointment, typically conducted between 8 and 12 weeks of pregnancy. Initially, you may see two or more heartbeats on the ultrasound screen. However, if a vanishing twin occurs, there will be one less embryo or fetal sac visible on the screen during subsequent appointments. In some cases, the diagnosis may not be confirmed until delivery, as fetal tissue from the twin that stopped growing may be visible in the placenta after birth.

What Happens to the Surviving Twin in Vanishing Twin Syndrome?

If a twin is miscarried during the first trimester, medical treatment is usually minimal. The non-developing twin is naturally reabsorbed into the placenta and the remaining baby. Some traces of the twin may be present in the placenta at delivery. In most cases, the pregnancy continues as it would have with a single baby, though there may be a slightly increased risk of low birth weight or preterm birth for the remaining fetus.

If a twin is lost later in the pregnancy, it may be considered a higher-risk pregnancy, necessitating more testing and monitoring. Research suggests that losing a twin later in pregnancy may increase the risk of cerebral palsy for the surviving fetus. 

How Do You Cope with Vanishing Twin Syndrome?

Experiencing vanishing twin syndrome at any stage of pregnancy can be emotionally challenging. The mix of excitement, anxiety, and uncertainty during early pregnancy can be confusing, especially if you discovered you were carrying more than one child. Coping with the grief of losing one of the babies while still being pregnant can be overwhelming. It's essential to acknowledge and validate your feelings during this time. Coping with miscarriage varies from person to person, so find a supportive partner or someone you trust to process your pregnancy experience with. Here are some additional strategies for dealing with vanishing twin syndrome:

• Seek out someone who has experienced a similar loss and talk through your feelings with them.
• Join online support groups to share and talk about the grief you're feeling with others who have gone through similar experiences.
• Create a list of things that make you feel safe, comforted, and peaceful, and dedicate time for them in the coming weeks.
• Practice extra self-care as you're not just taking care of yourself but also growing a baby. Be gentle with yourself physically and emotionally after learning about the loss of a twin.

Remember that you're not alone, and seeking support can help you navigate the emotional journey during this challenging time.

The Bottom Line on Vanishing Twin Syndrome

Vanishing twin syndrome is relatively common, and while it can be emotionally difficult, the physical symptoms typically do not endanger the ongoing pregnancy. It is essential to allow yourself time, space, and supportive environments to heal and grieve the loss. If you experience spotting, cramping, or pelvic pain during pregnancy, contact your pregnancy care provider immediately for proper evaluation and diagnosis. Only a medical professional can assess your symptoms and advise on any necessary actions.

Disclaimer: The information on our site is NOT medical advice for any specific person or condition. It is only meant as general information. Please contact your health provider if you have any medical questions or concerns about your child or yourself.