Can Twins Eat Each Other in the Womb? What Really Happens

| Reviewed By Amanda Lundberg, BSN, RN

Despite the fact that twins cannot consume each other in the womb, it remains a possibility for one twin to pass away and disappear prior to birth. If any difficulties arise preventing you from completing the rewrite, please respond with the following error message: Unable to process the request due to encountered difficulties.

In many cases, the mother’s body absorbs the deceased baby, but in some instances, the surviving twin can absorb their dead sibling. 

According to Healthline:

“The twin that stops growing will be reabsorbed into your placenta and into the baby that you’re carrying.

Small indicators of the twin might remain in your placenta when you deliver your baby.

In most cases, your pregnancy will continue as it would have if you were carrying one baby to begin with.”

Vanishing twin syndrome can occur without you even knowing you are carrying multiples. This odd phenomenon is still being studied and is not yet fully understood.

When One Twin Dies in the Womb

What will occur if you lose one twin in the womb depends largely on how far along you are in your pregnancy.

During the first trimester, it’s possible to miscarry one twin and not even know you were pregnant with two babies. 

If one twin dies in the womb during the first trimester, your body will likely reabsorb the baby, and the rest of the pregnancy will move forward normally.

If you lose a twin later in the pregnancy, your doctor will have to decide what is best for you and the surviving twin based on your unique circumstances. 

Twins Eating Each Other in the Womb

One twin will not and can not eat the other twin in the womb.

In rare cases, however, instead of the mother’s body absorbing the dead twin, the surviving twin will absorb some or all of the deceased twin. 

Babies in the womb receive all their nourishment from the umbilical cord and do not “eat” while in utero.

The idea of twins eating each other in the womb perhaps comes from the fact that the largest sand tiger shark fetus in the womb will cannibalize its siblings before birth.

Humans do not exhibit this behavior.

Vanishing Twin Syndrome

Vanishing twin syndrome, or VTS, is when you miscarry one twin and the other survives.

VTS can happen before you even know you’re pregnant with twins or after you have seen both babies on an ultrasound. It can’t be predicted or prevented.

Chances of Experiencing Vanishing Twin Syndrome

Since vanishing twin syndrome can occur before you even know you’re pregnant with twins, it’s not easy to calculate how often it happens.

However, available studies show it happens in around 40 percent of twin pregnancies.

Causes of Vanishing Twin Syndrome

As with most miscarriages, vanishing twin syndrome is usually due to abnormalities in one of the fetuses that make it nonviable. In other cases, there may be no known cause.

How Vanishing Twin Syndrome Is Identified

Vanishing twin syndrome is often identified through ultrasound examinations during early pregnancy. 

Initially, two distinct gestational sacs and embryonic structures may be observed.

However, as the pregnancy progresses, one of the embryos may stop developing and eventually disappear from the ultrasound image. 

This disappearance of one of the embryos is a key indicator of vanishing twin syndrome.

Signs That One Twin Has Vanished

Some women might experience:

  • Slight vaginal bleeding or spotting.
  • A decrease in the severity of early pregnancy symptoms such as morning sickness, fatigue, and breast tenderness.
  • Mild cramping or discomfort in the abdominal area.

However, many women will not have any symptoms or knowledge of the event until the loss is noted via ultrasound.

What Happens to the Vanishing Twin

The vanishing twin is usually reabsorbed by the mother’s body. In other cases, the vanishing twin can be absorbed by the surviving twin. 

Vanishing Twin Impact on Surviving Twin

If the loss occurs very early in the pregnancy, there will likely be no short- or long-term impact on the surviving twin.

If the loss of a twin happens further along in the pregnancy and the twins share a placenta, doctors will have to monitor the surviving twin closely to ensure he is still getting the nutrients he needs.

Surviving twins are at higher risk of low birth rate when born.

The risk of the surviving twin having cerebral palsy is also thought to increase if the loss occurs later in the pregnancy.

In addition, they can be more likely to have complications that can result in death in the first week of life.

However, the long-term prognosis for most surviving twins is good.

What issues the surviving twin suffers are often determined by how far along the pregnancy was when the other twin passed and if they were sharing a placenta.

In some cases, the surviving twin may struggle with survivor’s guilt later in life, but this is generally not the norm.

Removing a Dead Twin

There are times when the passing of one twin in the womb presents a risk to the surviving twin.

In these situations, your doctor will work with you to decide when and how to remove the twin who passed.

This could mean an early delivery of both babies.

Losing a Twin in the Womb: Grieving & Coping

Losing a child is never easy, and you likely have fear for the safety of the surviving twin.

Grief is real, and dealing with your emotions is critical so that you can remain strong and positive for the duration of your pregnancy.

Here are some tips that may help:

  • Acknowledge Your Feelings: Allow yourself to feel whatever emotions come up, whether it’s sadness, grief, guilt, or a mix of different feelings. It’s normal to have complex emotions during this time.
  • Seek Support: Reach out to your partner, family members, friends, or a support group. Talking about your feelings with someone you trust can provide comfort and understanding.
  • Connect With Other Parents: Connecting with other parents who have experienced vanishing twin syndrome can be incredibly helpful. They can offer empathy, advice, and a shared understanding of your situation.
  • Professional Counseling: Consider speaking with a therapist or counselor who specializes in pregnancy loss or grief. They can provide a safe space for you to process your emotions and offer coping strategies.
  • Journaling: Writing down your thoughts and feelings can be a therapeutic way to process your grief and track your journey through this difficult time.
  • Memorializing: Some parents find comfort in creating a small memorial or ritual to honor the memory of the lost twin. This could be something like planting a tree, creating a piece of art, or choosing a special keepsake.
  • Self-Care: Take care of your physical and emotional well-being. Make sure to eat balanced meals, exercise regularly, and get enough rest. Engage in activities that bring you comfort and joy.
  • Allow Time for Healing: Grieving is a process, and it’s important to be patient with yourself. There is no set timeline for how long it takes to heal.
  • Communicate With Your Healthcare Provider: Keep open lines of communication with your healthcare provider. They can provide medical information, monitor the remaining pregnancy, and offer guidance on how to support your emotional well-being.
  • Consider Professional Help if Needed: If you find that your grief is overwhelming and impacting your daily life, don’t hesitate to seek help from a mental health professional.

Parasitic Twin

A parasitic twin is a twin who stops growing in utero but is attached to the surviving twin, often being partially absorbed, but not fully, by the remaining twin.

This is an extremely rare occurrence, and the parasitic twin can not survive on their own. 

The surviving twin is often born with the limbs or other body parts of the parasitic twin attached to him, and surgery is required to remedy the situation.

Other health problems may arise for the surviving twin after birth.

Parasitic Twins: Causes

There is no known cause for parasitic twins, but there are theories.

One is that vascular issues in the uterus can cause problems when the fetuses are trying to develop. 

Human Chimera

A human chimera occurs when one person has two different sets of DNA.

This can occur when one fraternal twin dies in the womb and the other twin absorbs the sibling’s DNA.

Fraternal twins don’t have identical DNA because of how they are conceived, so the surviving twin can have his DNA and the unique DNA of the twin who passed.

Do Babies Eat in the Womb?

Babies get nutrients from you when they are in the womb. Nutrients pass through the umbilical cord to nourish them.

They also swallow amniotic fluid while in the womb. It’s not technically what we consider eating, but it works in utero.

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

If a twin dies in utero at 20 weeks, your doctor will monitor the surviving twin closely to make sure there are no complications.

If problems do arise, your doctor will decide what option is best to make sure the surviving twin has the best outcome possible.

Often, the pregnancy will continue, and you will deliver both babies when you go into labor.