How does Vanishing Twin Syndrome happen?
Early confirmation of multiple pregnancy is relatively easy when two or more embryonic sacs are seen on the ultrasound screen. The earliest stage when fetal heartbeats can be visualized is at around 6 weeks of gestation. But when subsequent ultrasounds after the initial one are carried out and only one viable sac can be seen, or only one heartbeat heard, then the diagnosis of Vanishing Twin Syndrome is given.
Diagnosing a twin pregnancy is more common thanks to the widespread use of fertility assistance and closer pregnancy monitoring.
Why does Vanishing Twin Syndrome happen?
The truth is that medical professionals are not 100% sure why it happens but many explanations have been put forward, including Major genetic or chromosomal abnormalities—which mean that the embryo is simply not viable—or improper cord implantation.
How frequently does Vanishing Twin Syndrome occur
What can I do to prevent Vanishing Twin Syndrome from happening?
In cases of repeated miscarriage for no obvious reason, genetic counselling may become necessary. Speak with your health care practitioner if this is an option you wish to investigate.
What are the symptoms of Vanishing Twin Syndrome?
However, if she has conceived through fertility assistance and is having regular blood tests, there is likely to be a reduction noted in her circulating pregnancy hormones. This may be the earliest indication that a mother was pregnant with twins or triplets, but one of them has miscarried.
Unlike a miscarriage though, the pregnant mother may not have any vaginal bleeding or uterine cramping. This really depends on the stage of pregnancy in which the miscarriage occurs.
It’s easy for mothers to interpret vaginal bleeding as a complete miscarriage and an indication that they are no longer pregnant. But if twins or triplets have been conceived and only one of them miscarried then the other baby is likely to mature in the usual way.
Unless a mother has been told she is pregnant with twins or multiples, she may not even be aware she has miscarried one of them. If, however, one of the embryos dies in the second or third trimester, there can be some increased risks with the remaining one. Premature birth can become a higher risk, as can the risk of cerebral palsy.
If the miscarriage occurs before eight weeks of gestation, the water and fluids from the miscarried embryo are reabsorbed and there is nothing to be seen. But if the miscarriage happens after this time, the tiny, compressed fetus can sometimes be seen at the birth of the other twin as they are both expelled from the uterus. This may be the first indication that twins were initially conceived though only one matured to delivery.
Sometimes a second or third trimester miscarriage of one twin can cause significant obstetric problems. Premature labor, infection, bleeding and an increased risk of birth complications can all occur with a late stage miscarriage of one twin.
What about the remaining twin?
In most cases, the surviving twin is not affected by the miscarriage of the other. They continue to grow and mature to full gestation without any complications. However, recent studies have found that around 7% of women who have experienced Vanishing Twin Syndrome will deliver the other baby or babies prior to 28 weeks of gestation. There is also an increased risk of the surviving baby or babies having low birth weight. There is also potentially a greater risk of the surviving twin or triplet having health issues later in life.
If your health care practitioner is aware of Vanishing Twin Syndrome, they will monitor your pregnancy extra carefully. If you are an Rh-Negative blood group your blood will be tested for antibodies. You may need to have an injection of Anti-D after your baby is born to protect any future babies you may carry.
What is the treatment for Vanishing Twin Syndrome?
Is it normal to feel sad?
Most importantly, seek support. Speak with your pregnancy care provider, midwife or obstetrician about counselling options.
The information of this article has been reviewed by nursing experts of the Association of Women’s Health, Obstetric, & Neonatal Nurses (AWHONN). The content should not substitute medical advice from your personal healthcare provider. Please consult your healthcare provider for recommendations/diagnosis or treatment. For more advice from AWHONN nurses, visit Healthy Mom&Baby at health4mom.org.