What does a “vanishing twin” mean?
It is a well established fact that only a proportion of twins starting off as such actually continue as twins to delivery. If all twin pregnancies were identified early enough by ultrasound scan (at six to ten weeks), it is estimated that one twin will subsequently be lost in between 30 and 50 per cent of all. Twins delivered therefore represent only a proportion of pregnancies that started as such and a substantial proportion of babies born as singletons started off as twins. The other twin, by implication, vanished. The twin that is lost, usually with such minimal symptoms and at such a very early stage of the pregnancy that the mother hardly notices, is known as a ‘vanishing twin’.
