Marked Growth Discordancy in Three Sets of Twins Associated with Velamentous Insertion of the Umbilical Cord of the Smaller Twin

The incidence of velamentous insertion of the umbilical cord is increased in multiple gestations. In singleton and twin gestations, this condition has been associated with lower mean birth-weight. We present three sets of twins (two monozygotic and one dizygotic) in which marked growth discordancy, ranging between 25 and 50%, was associated with velamentous insertion of the umbilical cord of the smaller twin in the absence of any other obvious pathology. In cases of marked growth discordancy in twins, velamentous insertion should be considered a possible etiology, and sonographic inspection of the placental insertion of the umbilical cord, particularly of the smaller twin, performed.