Twin pregnancy

Abstract

Maternal morbidity and mortality rates are much higher in twin than in singleton pregnancy due to preterm labour, haemorrhage and pregnancy induced hypertension. The perinatal mortality rate is in twins 3-4 times higher than in the case of singletons, as a result of chromosomal abnormalities, prematurity, hypoxia and trauma during labour and delivery. Since monozygotic twinning itself may result from a teratogenic event, the frequency of malformations is increased in twins as compared to singletons and is almost entirely due to the high incidence of structural defects in monozygotic twins. Perinatal mortality and morbidity for twins compared to singletons remain high and the primary reason is premature labour and delivery. Several different treatment modalities have been proposed and have been directed primarily toward the prevention and treatment of premature labour. These treatment modalities have included prophylactic bed rest, cervical suture placement and beta-sympathomimetic agents. Low birth weight is a common problem in twins and is a result of prematurity as well as intrauterine growth retardation (IUGR). IUGR affects approximately 15% to 30% of twin pregnancies. Twin-twin transfusion syndrome (TTS) is a serious complication of monochorionic gestations with a reported incidence of 5% to 30% of monochorionic twin pregnancies and in severe and untreated cases is associated with high rates (56-100%) of perinatal mortality. Ultrasonography helps to evaluate twin pregnancies for amnionicity and chorionicity, growth retardation, oligy-polyhydramnios, twin-twin transfusion syndrome and other complications.