Vanishing Twin Syndrome: Twin Miscarriage

What is Vanishing Twin Syndrome?

Vanishing Twin Syndrome is when a twin or multiple disappears during pregnancy as a result of a miscarriage of one twin or multiple. The miscarried twin or multiple dies in the womb and is partially or completely reabsorbed. The vanishing twin is absorbed by the other twin or multiples or the mother.

What are the signs of Vanishing Twin Syndrome?

Unlike other miscarriages, there are generally no signs of Vanishing Twin Syndrome. The miscarriage usually happens early on in the pregnancy, in the first trimester. In the majority of cases, the surviving twin is not affected by the miscarriage of the other twin. Usually the pregnancy continues as if nothing had happened. If Vanishing Twin Syndrome occurs later in the pregnancy, the surviving fetus has an increased risk of cerebral palsy and / or being born prematurely.

How often does Vanishing Twin Syndrome occur?

Vanishing Twin Syndrome was first recognized in 1945. Documented rates of Vanishing Twin Syndrome have grown significantly over the past few decades. This is  due to the fact that twin pregnancies are caught earlier on by means of early ultrasound. Also, due to the widespread use of fertility assistance, many pregnancies are monitored closely and detected very early on. Vanishing Twin Syndrome has been documented to occur in 21-30 percent of multiples pregnancies.

Are there any signs of an absorbed twin?

Normally there are no signs of the absorbed twin. Nevertheless, in very rare cases, the vanished twin becomes “mummified” and are born at delivery. Rather than being completely reabsorbed, the dead fetus will be compressed by its growing twin to a flattened, parchment-like state.  At delivery, the deceased baby may be identified as fetus compressus or fetus papyraceous. In other cases, the surviving twin gets some of the deceased twin’s cells and becomes a chimera. A chimera is one person with two sets of DNA. It’s extremely rare, but there are a few people in the world who are chimeras. For instance an American woman who had to fight in court to prove, that the children that she had given birth to, was her own.