Abstract: As high risk pregnancy，twin pregnancy increases the morbidity and mortality of maternal-fetal complications. Recently，more and more obstetricians paid attention to the problems caused by the increased incidence of twin pregnancy. Therefore，antenatal surveillance can help to reduce the maternal-fetal complications and improve mother and child outcome through early diagnosis of abnormal fetals. Ultrasound contributes to determination of chorionicity，amnionicity and placentas，assessment of fetal growth and screening for anomalies in twin pregnancy. Rational prenatal ultrasonography is reliable method for the diagnosis and assessment of twins and provide evidence for clinical treatment.

Key words: Pregnancy, multiple, Twins, Ultrasonography, prenatal, Prenatal care