Pregnant With Twins and Miscarrying One: Explained Simply

| Reviewed By Amanda Lundberg, BSN, RN

It is possible for a person to become pregnant with twins, experience a miscarriage of one twin, and still carry the other to full term.

Typically, the loss of one twin happens very early in the pregnancy, often before a mother even knows she is pregnant.

This phenomenon is called vanishing twin syndrome. Miscarrying a twin later in pregnancy is much rarer.

According to an excerpt from PubMed:

“Vanishing twin syndrome … is a condition in which one of a set of twins or multiple embryos dies in utero, disappears, or gets resorbed partially or entirely … portraying the image of a vanishing twin.”

Understanding Vanishing Twin Syndrome

Vanishing twin syndrome is a phenomenon that occurs when a woman becomes pregnant with twins but one of the embryos fails to develop and is absorbed by the other twin, the placenta, or the mother’s body.

This can happen in the early stages of pregnancy, often before the mother is even aware she is carrying twins.

The gestation of the remaining baby proceeds as normal.

If a baby in a multiple pregnancy is lost later in the pregnancy (after 20 weeks), the loss is typically called a twin loss.

Causes

The exact cause of vanishing twin syndrome is not known.

Doctors speculate that it occurs when one twin has chromosomal abnormalities that would not sustain life and the other is healthy.

Experts usually attribute this condition to either genetic abnormalities in the baby or possibly improper umbilical cord implantation. 

Likelihood of Occurrence

Roughly 20-30% of twin pregnancies will experience vanishing twin syndrome. 

In my close friend’s twin pregnancy 6 years ago, Baby B (a girl) had a “significantly lower heart rate” at their 6-week ultrasound.

The doctor prepared her to come back at 8 weeks and see that her baby had, in fact, vanished. 

We all count ourselves so blessed that her heartbeat was perfectly strong at the 8-week checkup and has beat strongly ever since! 

Odds of Miscarrying Both Twins 

There is only a 5-10% chance of losing both twins to miscarriage. This knowledge could help relieve any anxiety you may be feeling.

Instead of focusing on the small possibility of miscarrying both babies, focus on the 90-95% chance that this will not occur.

Odd of Miscarrying One Twin 

There is a greater chance of losing one twin in a twin pregnancy than there is of losing both twins.

Doctors call this vanishing twin syndrome, and it usually occurs early in the pregnancy.

The probability of this condition is higher at 20%-30%. This rate of miscarriage is almost double that of pregnancies involving a single baby. 

Misdiagnosis of Vanishing Twin Syndrome

In some cases, particularly if the initial ultrasound is performed very early in pregnancy, it is possible for one twin to be less visible or not detectable due to its position or size.

This could potentially lead to a mistaken diagnosis of vanishing twin syndrome.

Subsequent ultrasounds as the pregnancy progresses may reveal the previously “hidden” twin. 

Symptoms of Vanishing Twin Syndrome

Because this event usually happens so early in pregnancy, there often aren’t many noticeable symptoms.

Some women might cramp or bleed a bit, but both of those symptoms can be common during the first weeks of pregnancy.

The only way to actually document vanishing twin syndrome is through ultrasound as blood levels aren’t sensitive enough to detect the change.

When Vanishing Twin Syndrome Often Occurs

Vanishing twin syndrome typically occurs very early in the pregnancy, sometimes before a mother even knows she is expecting twins.

The vast majority of cases of Vanishing Twin Syndrome occur before 12 weeks.

Confirming Vanishing Twin Syndrome

Vanishing twin syndrome is typically confirmed through ultrasound imaging. 

During early prenatal care, when a woman undergoes an ultrasound examination, her healthcare provider may detect the presence of multiple gestational sacs or embryos. 

If one of the embryos fails to develop and is absorbed by the mother’s body, it will no longer be visible on subsequent ultrasounds.

In some cases, a woman may experience symptoms like bleeding or cramping, which could lead to further investigation. 

If a vanishing twin is suspected, a healthcare provider may order additional tests, such as blood tests to monitor hormone levels or other imaging studies to rule out other potential causes of symptoms.

Effects on Mother and Remaining Twin

Learning about the vanishing twin can be emotionally distressing for the mother.

She may experience a range of emotions, including sadness, grief, guilt, and confusion.

In most cases, the mother’s body will naturally absorb the tissue of the vanishing twin, which is generally not associated with significant physical complications.

However, there may be some mild discomfort or spotting.

In some cases, the occurrence of a vanishing twin can slightly increase the risk of complications for the surviving twin, such as a higher chance of premature birth or low birth weight.

This is more common when the vanishing twin is lost later in pregnancy.

Healthcare providers may closely monitor the pregnancy to ensure the remaining twin is developing properly and receiving sufficient nutrients and oxygen.

The remaining twin is not aware of the vanishing twin’s disappearance, so there are typically no psychological effects on the surviving twin.

Once the pregnancy progresses and the surviving twin is born, there are generally no long-term effects associated with vanishing twin syndrome.

The surviving twin’s development and health are primarily influenced by genetics and environmental factors.

Treatment & Recovery

In most cases of vanishing twin syndrome, specific medical treatment is not typically required.

The body usually handles the absorption process without the need for intervention.

Healthcare providers will closely monitor the health and development of the remaining twin through regular prenatal check-ups, including ultrasounds and other necessary tests.

Emotional support is crucial for women who have experienced vanishing twin syndrome. Grief, sadness, guilt, and other complex emotions are common reactions. 

Counseling or therapy can provide a safe space for the mother to process her feelings and receive support.

Preventing Vanishing Twin Syndrome

Vanishing twin syndrome is not something that can be prevented as it is a natural and spontaneous occurrence that happens early in pregnancy. 

It is believed to be primarily due to chromosomal abnormalities or other developmental issues in the embryo.

Factors leading to vanishing twin syndrome are typically beyond anyone’s control, and they are not influenced by lifestyle choices, behaviors, or medical interventions.

Risk Factors for Miscarriage

Some women are at a higher risk for both miscarriage and vanishing twin syndrome.

  • Women over the age of 35 typically have a greater risk of miscarrying.
  • Risk factors include chronic conditions, previous history of miscarriages, and the mother being either overweight or underweight.
  • Some women who have cervical or uterine complications might have a higher risk of miscarriage.
  • Women who smoke or use illicit drugs or alcohol when pregnant are more likely to have a pregnancy loss. 

When Does Miscarriage Risk Drop? 

The risk of miscarriage drops dramatically after the first trimester or 12 weeks of pregnancy, and 80% of miscarriages occur in the first 12 weeks.

Any pregnancy loss after 20 weeks is considered to be a stillbirth, not a miscarriage.

Does Miscarriage Happen Suddenly? 

Miscarriage can happen rather quickly, or it can be a process that takes a couple of weeks.

Vanishing twin syndrome is thought to happen quickly and without warning. 

Can a Miscarriage Be Stopped? 

Once a miscarriage has started, there is no way to stop it.

The signs of miscarriage are the final sign that the pregnancy is not developing successfully and has already ended.

It is always important to remind women that a miscarriage is not the result of them doing something wrong and it is not their fault. 

Miscarriage Symptoms in the First Trimester

Symptoms of an early pregnancy loss are vaginal bleeding and spotting.

This spotting is often accompanied by cramps in the lower back and abdomen. The final symptom is fluid or tissue passing through the vagina. 

Can You Miscarry and Still Be Pregnant?

You can miscarry and still be pregnant if you are having multiples. One baby can survive while the other twin vanishes.

However, if you are pregnant with just one baby and that pregnancy stops developing for any reason, your body will expel the baby or your doctor will remove the baby in a procedure. 

Do Miscarriages Run In Families?

There is some research that proposes that the predisposition to miscarry can be passed from mother to daughter.

However, over 50% of miscarriages occur because of genetic abnormalities that occur as the embryonic cells split and divide, not from a hereditary condition.