Obstetric complications of twin pregnancies.

Advances in assisted reproductive technology and increases in the proportion of maternities in older women have both contributed to the steep increase in the incidence of twin pregnancies since the 1980s. Maternal and perinatal complications are higher in twins than in singleton pregnancies. A significant proportion of perinatal mortality and morbidity among twins is due to the high incidence of preterm delivery and the added complication of twin-to-twin transfusion syndrome (TTTS) in monochorionic twins. Monochorionic twins also have a much higher rate of perinatal mortality than dichorionic twins, the greatest risk being before fetal viability (<24 weeks gestation). Early diagnosis of twins and their chorionicity, close fetal surveillance, particularly of monochorionic twins, and prompt therapeutic intervention in TTS are necessary to reduce perinatal mortality. Intrapartum management in the hospital setting with anaesthetic and neonatal facilities, as well as critical assessment of mode of delivery, have led to better outcomes. Ultrasonography is a valuable tool in the management of twin pregnancy. This chapter briefly summarises these topics, with a particular focus on recent literature.