Complications occuring in the fetus or neonate

In twin pregancies there is an excess mortality and morbidity; monozygotic twins have a mortality nine times that of singletons, dizigotic three times.

Complications include:

• congenital malformations - neural tube defects, heart abnormalities, incidences of Turner's and Klinefelter's syndromes are all increased. Overall, malformations occur twice as often in twin than in singleton pregnancies
• twin to twin transfusion
• preterm delivery and low birth weight, as discussed elsewhere
• respiratory distress syndrome and infection