Mothers who are carrying multiple fetuses are affected in this unusual medical condition. In vanishing twin syndrome one or more of the fetuses may die and then be fully reabsorbed by the mother’s body. It will typically happen in the first trimester and leave minimal traces behind. It is also referred to as twin embolisation syndrome.
Vanishing twin syndrome usually does not cause any complications and commonly goes unremarked. In some rare cases instead of the fetus being reabsorbed by the mother it will become compressed and dessicated by its siblings or sibling. If this happens the fetus will be delivered in a flattened state at the stage of development that was reached before the fetus died. This is referred to as fetus papyraceus.
It was first recognized in 1945. Approximately twenty to thirty percent of multiple pregnancies are affected by this syndrome meaning that many single births actually started out as twins or multiples. An estimated one in eight pregnancies started as twin pregnancies. In some cases the sibling that survived can develop psychological problems called twinless twin. They sometimes experience guilt, loss, confusion, and other emotions that suggest they were affected by the loss of the other fetus. The women that vanishing twin syndrome affects the most are over thirty years of age and who use techniques such as hormones to help become pregnant.
Many times the mother may be totally unaware of the situation but other times the mother may have breakthrough bleeding, pelvic cramps, or mild cramps. These symptoms are similar to having a miscarriage. There may also be a decrease in hormone levels.
The cause for a mother to have vanishing twin syndrome is not known but there are a few of theories as to why this might happen. It could be:
- The result of a congenital malformation that is not compatible with life
- The lack of access to the needed nutrients for both fetuses
- Improper cord implantation
- Chromosomal abnormalities
- Placental abnormality
- Blighted ovum
What is known is that when the fetus dies it is absorbed by the mother’s body and remaining siblings or sibling. As the exact cause of a mother having vanishing twin syndrome is not known there is usually nothing that could have been done to prevent it so a woman should not blame herself if it happens.
Vanishing twin syndrome is usually diagnosed as part of a routine follow-up ultrasound when the physician finds that the two heartbeats heard earlier have dwindled to one heartbeat.
There is no special medical care needed if this happens in the first trimester but if occurs in the second or third trimester the physician may treat it as a high-risk pregnancy.
If it occurs after the first trimester it could result in premature labor, hemorrhage, obstruction of the cervix if it becomes a fetus papyraceus, or infection. There is also the possibility that the surviving fetus could develop cerebral palsy, especially if the vanishing twin syndrome occurred in the second trimester.