A vanishing twin, also known as disappearing twin, is the term for a fetus that started to grow as a twin but whose growth stopped early after fertilisation. The fetus can appear to be painted on a translucent sheath of skin after birth and could be described as having a "fossilised" look.

One theory for the creation of a vanishing twin is due to an atypical fertilisation process. Vanishing twin is thought to occur when there is only one chorion formed. This causes the vanishing twin to be squashed flat against the sac of the other twin as it is out-competed for space.

According to research, this happens in one out of every eight pregnancies and may not even be known in most cases. However, there are cases where this can create further complications in the pregnancy like slow growth of the fetus and premature deliveries. It is also argued that the children who are born in such a pregnancy may have some memories of their vanishing twins and, because of this, may have some feelings of loneliness.

External links

• Wombtwin Survival Research and Stories
• Vanishing twin occurance in India