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Ultrasound appointments when pregnant to see your baby are usually very exciting. Seeing your child before it’s even out is a memory to cherish. Unfortunately, for some, it isn’t always rainbows and sunshine as a few abnormalities can also be discovered during this procedure. One of them is the sudden absence of a second foetus.Â
One day back in 1945, a man named Stoeckel discovered that the number of multigestational pregnancies i.e. pregnancy with more than one foetus (twins, triplets etc) was more than the number of multigestational births. This phenomenon where the pregnancy starts with two babies and ends with one is known as vanishing twin syndrome.
Vanishing twin syndrome occurs when one of a set of twins or multiple embryos passes away in the uterus, leading to a singleton pregnancy. This condition typically happens in the first trimester when one embryo stops developing while the other continues to grow. Sometimes, the absorbed embryo leads to a miscarriage, but the surviving one keeps growing normally.
It’s difficult to determine how common vanishing twin syndrome is because many people might lose an embryo before their first pregnancy ultrasound. So, those who have early ultrasounds are more likely to find out that an embryo they once had has disappeared. Estimates suggest that vanishing twin syndrome happens in 21-30% of pregnancies with multiple foetuses.
In vanishing twin syndrome, one of the embryos detected early in pregnancy stops growing and is absorbed. If multiple embryos are seen in early ultrasounds, one may not be found later because it has stopped developing. This can cause miscarriage, often with vaginal bleeding or spotting in the first trimester. The vanished twin may undergo different changes.
Resorption: In vanishing twin syndrome, resorption is when the tissues of the vanished twin are naturally absorbed by the mother’s body or the surviving twin. This usually happens in the first few months of pregnancy without causing harm to the surviving twin. It allows the remaining foetus to continue growing normally.
Blighted Ovum: This occurs when an ultrasound shows an empty sac alongside a normal one. The empty sac is usually expelled during the first trimester, sometimes causing vaginal bleeding. It’s important to have an ultrasound before any procedures to avoid harming the surviving twin.Â
Foetus Papyraceous: This happens when the deceased twin becomes flattened and compressed. It’s often seen in multiple pregnancies but is relatively rare. If the twin vanishes early, complete absorption occurs. If it happens later, the vanished twin may affect the surviving twin. The surviving twin might suffer from physical malformations or growth restrictions due to the compromised uterine environment.
Vanishing twin syndrome typically has unknown causes but can occur when genetic irregularities in one twin prevent it from fully developing. These genetic issues are often present from conception and cannot be controlled or prevented. Incorrect cord implantation or a small sized placenta in the deceased twin may also be a cause.
The signs of vanishing twin syndrome are similar to common first-trimester pregnancy symptoms, making it hard to detect the loss of one embryo in a twin or triplet pregnancy. Symptoms include:
If you experience any pelvic pain or unexplained bleeding during pregnancy, contact your healthcare provider.
Certain factors are considered to be associated with the loss of a foetus, including:
The use of ultrasound has led to more frequent diagnoses of vanishing twin syndrome in early pregnancy. Before ultrasound technology was available, doctors diagnosed the death of a twin or multiple after birth by examining the placenta.
Nowadays, early ultrasounds in the first trimester can detect the presence of twins or multiples. Sometimes, a follow-up ultrasound may show the disappearance of one twin. As earlier mentioned, some women may experience symptoms suggestive of a miscarriage, even though an ultrasound shows only one baby in the uterus.
If an embryo vanishes in the first trimester, the mother often doesn’t notice. The pregnancy generally continues without complications, and both the mother and the surviving twin are usually unaffected.Â
The remaining foetus has a high chance of survival, and the pregnancy proceeds normally. In the second or third trimesters, losing a twin poses greater risks. These pregnancies are classified as high-risk and need closer monitoring by healthcare providers.
In vanishing twin pregnancies, there’s a greater risk of foetal malformations and other complications, like cerebral palsy or growth problems in the surviving twin.
Maternal complications, such as gestational diabetes or premature labour, are also more common compared to singleton or twin pregnancies.
When a twin is lost during pregnancy, the timing matters a lot. An early loss (in the first trimester) usually means the second twin will have a normal pregnancy course. But if a loss happens later, it’s riskier and needs extra medical care to handle possible problems.
No specific medical care is needed for a simple vanishing twin in the first trimester. Neither the surviving twin nor the mother would require medical treatment. However, if foetal loss occurs in the second or third trimester, the pregnancy may be considered high-risk and will hence be monitored closely.
Pregnant women should seek medical attention if they experience bleeding, cramping, or pelvic pain. An ultrasound will be performed to ensure that no viable foetus remains before considering a dilation and curettage (D&C) procedure, a surgery procedure after a first-trimester miscarriage. Dilation means opening the cervix, while curettage means removing the uterus’s contents. In many cases, the woman can opt to wait for a natural miscarriage.
Regular prenatal check-ups and ultrasounds are important to monitor the pregnancy and find any foetal issues linked to losing a twin. Though most cases of vanishing twin pregnancies go smoothly, research suggests the surviving twin might have a slightly lower birth weight than twins where both babies survive.
Preventing vanishing twin syndrome is tricky because healthcare practitioners don’t fully understand why it happens. But you can lower the risk by staying healthy during pregnancy, getting regular check-ups, and following your doctor’s advice, especially if you’re using fertility treatments. While we can’t always prevent it, taking care of yourself can improve your chances of a healthy pregnancy.
Although vanishing twin syndrome might not directly impact later pregnancies, factors like maternal age could increase risks. Those who’ve had this syndrome should stay monitored and consult healthcare providers for future pregnancies. With careful attention and medical advice, risks can be identified and managed for a healthier pregnancy.
Most surviving twins of vanishing twin syndrome grow up without major health problems. However, researchers are studying the long-term effects on their physical health, thinking abilities, and emotions. This research aims to enhance medical care and support for those affected by the syndrome.
Vanishing twin syndrome might be caused by genetic issues in one of the twins, impacting how the embryo develops. But there is still a need for more research work to be done to fully understand these genetic factors. Figuring this out could improve how to prevent and treat the syndrome in the future.
Preventing vanishing twin syndrome is tricky because healthcare practitioners don’t fully understand why it happens. But you can lower the risk by staying healthy during pregnancy, getting regular check-ups, and following your doctor’s advice, especially if you’re using fertility treatments. While we can’t always prevent it, taking care of yourself can improve your chances of a healthy pregnancy.
Although vanishing twin syndrome might not directly impact later pregnancies, factors like maternal age could increase risks. Those who’ve had this syndrome should stay monitored and consult healthcare providers for future pregnancies. With careful attention and medical advice, risks can be identified and managed for a healthier pregnancy.
Most surviving twins of vanishing twin syndrome grow up without major health problems. However, researchers are studying the long-term effects on their physical health, thinking abilities, and emotions. This research aims to enhance medical care and support for those affected by the syndrome.
Vanishing twin syndrome might be caused by genetic issues in one of the twins, impacting how the embryo develops. But there is still a need for more research work to be done to fully understand these genetic factors. Figuring this out could improve how to prevent and treat the syndrome in the future.
1. American Pregnancy Association. “Dilation and Curettage (D&C) Procedure After Miscarriage.” American Pregnancy Association,
2. American Pregnancy Association. “Vanishing Twin Syndrome.” American Pregnancy Association,
3. Cleveland Clinic. “Vanishing Twin Syndrome.” Cleveland Clinic,
4. Ismail, K.M., and Law, D.J. “Vanishing Twin Syndrome: Is it Associated with Adverse Perinatal Outcome?” QxMD,
5. Wittmann, B.K., and Koller, O. “Vanishing Twin Syndrome: Diagnostic and Clinical Implications.” PubMed,
6. Zamani Z, Parekh U. Vanishing Twin Syndrome. [Updated 2023 July 25]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from:
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