Vanishing Twin Syndrome

Vanishing twin syndrome (VTS) is a type of miscarriage that can occur during a multiple pregnancy (two or more embryos). It happens when an embryo seen on an early ultrasound no longer appears on a later one.

The embryo stops growing. Typically, your body and/or the surviving embryo(s) partially or fully absorb the tissue. VTS usually happens during the first trimester. But it can also happen later in pregnancy.

Experiencing VTS can cause a rollercoaster of emotions and questions. Talk to your healthcare provider about what it means for your pregnancy. Support from loves ones or a therapist can help you cope.

Types

The vanishing twin has one of the following outcomes:

• Reabsorption: Your body or the surviving embryo absorbs the tissue. This is the most common outcome and usually doesn’t affect your pregnancy.
• Blighted ovum: A fertilized egg implants in your uterus but doesn’t grow into an embryo.
• Fetus papyraceous: One fetus dies in early pregnancy. It’s squeezed between membranes and your uterine wall. After a while, the deceased fetus becomes mummified. It looks like parchment paper. This is very rare.

Symptoms of vanishing twin syndrome

Most cases of vanishing twin syndrome don’t cause symptoms. Your body often absorbs the embryo without any signs. But in some cases, you may notice light vaginal bleeding, mild cramping or pelvic pain in the first trimester.

These signs can look like normal early pregnancy symptoms, so many people don’t know they had a vanishing twin.

Vanishing twin syndrome causes

Researchers don’t know the exact cause of VTS. They believe it could stem from issues with:

• Chromosomes in the vanishing embryo
• The placenta
• Implantation

You can’t prevent vanishing twin syndrome. It’s natural to wonder if you could’ve done something different. But these issues aren’t your fault or something you can control. Be kind to yourself.

Risk factors

You may have a higher chance of vanishing twin syndrome if you:

• Are pregnant with three or more embryos
• Are 35 or older
• Have a long-term health condition (like diabetes or lupus)
• Have had intrauterine growth restriction (IUGR) in past pregnancies
• Have a subchorionic hematoma

Complications

Studies show mixed results on whether VTS leads to complications. Some studies suggest VTS may raise the risk of preterm birth or slow growth in the surviving fetus. Others show it has no major effect.

Talk to your provider about what this means for you. It’s impossible to predict exactly how any pregnancy or birth will go. But they can monitor your pregnancy and help guide your care.

How doctors diagnose this condition

Your healthcare provider may diagnose VTS during an ultrasound when they see that one of the embryos is no longer present.

They may also check your levels of human chorionic gonadotropin (hCG). A slower rise in hCG compared to typical twin pregnancies could be a sign of VTS.

Sometimes, people lose an embryo before the first ultrasound. In that case, neither you nor your provider may know there was a twin.

In some cases, your provider may find tissue from the vanished twin in the placenta after delivery. Before ultrasound, this was the only way to confirm VTS.

How common is vanishing twin syndrome?

Many people lose an embryo before their first ultrasound, so the true number isn’t known. Studies estimate that VTS happens in 15% to 35% of all twin pregnancies. It affects about half of pregnancies with three or more embryos.

Healthcare providers are more likely to catch cases of VTS in IVF pregnancies. That’s because you typically get ultrasounds earlier in pregnancy when doing IVF.

How is it treated?

There’s no treatment for vanishing twin syndrome. If it happens in the first trimester, it usually doesn’t affect the surviving fetus.

If it happens later in pregnancy, your provider may monitor you more closely. They may classify your pregnancy as high-risk.

Is there anything I can do to feel better?

Coping with vanishing twin syndrome can be tough. You may feel grief while still being pregnant, which can be confusing and emotional.

Give yourself time and care. Talk to your partner, friends or a mental health provider. A therapist or grief counselor can help you process your feelings.

Ask your provider what to expect during the rest of your pregnancy. Knowing what’s ahead can ease anxiety and help you focus on your health.