ABSTRACT
The incidence of fetal malformations is higher in multifetal pregnancies than in singletons1,2. In dizygotic twin gestation the risk per pregnancy of a fetal malformation is slightly more than double (independent probabilities per fetus). In a monozygotic twin gestation there is an increased risk of structural malformation. Table 64.1 lists the structural malformations in twins3. The presence of a fetus with a major anomaly in a twin gestation increases the risk of preterm delivery4.
