Objective To review the diagnosis,monitoring,management and perinatal outcomes of monochorionic monoamniotic (MCMA) twin pregnancy.Methods From July 2010 to August 2013,there were 17 MCMA twin pregnancies diagnosed and delivered in Shanghai First Maternity and Infant Hospital.According to the MCMA management protocol,induced abortion,elective fetal reduction,and anticipant pregnancy were optional.For those anticipant pregnancies,fetal lung underwent maturation promotion at gestational weeks 28; hospitalization with 40 min/day continual fetal electronic monitoring and umbilical blood monitoring twice weekly at gestational weeks 28-30; 40 min continual fetal electronic monitoring twice daily and umbilical blood monitoring once every other day at gestational weeks 30-32; and 40 min continual fetal electronic monitoring three times daily and umbilical blood monitoring once daily at gestational weeks 32-34; and pregnancy ended on time.The presence of umbilical cord entanglement,congenital malformation,intrauterine fetal death,complications exclusive to monochorionic twins (e.g.selective fetal growth restriction,twin reversed arterial perfusion sequence and twin-twin transfusion syndrome) and the perinatal outcomes were retrospectively analyzed.Results Average maternal age of women with 17 MCMA twins was (29.0±2.7) years,and all were primiparas.They were diagnosed at (18.6± 5.5) weeks on average (11 +5-28+1 weeks).Umbilical cord entanglements were detected in all cases by ultrasonography and confirmed postnatally.There were three cases of complications specific to monochorionic twins,including two with selective fetal growth restriction and one with twin reversed arterial perfusion sequence.There were seven women with fetal congenital malformation; four of whom chose induced abortion; one case of anencephaly chose radiofrequency ablation fetal reduction,and the remaining two cases with congenital malformation and ten cases without chose anticipant pregnancy,and there were no abnormal ultrasonography signs during pregnancy.Among these 12 cases,intrauterine fetal death of both fetuses occurred in two cases at 16 and 21+1 weeks gestation and they were aborted.Intrauterine fetal death of a single fetus occurred in one case at 30+2 weeks gestation (another fetus was delivered by emergency cesarean section).There were a total of eleven live births delivered by cesarean section (four by emergency cesarean section) at a median gestational age of (32.7± 1.6) weeks.There were 20 live neonates with a mean birth weight of (1 850±496) g.Sixteen neonates were transferred to the neonatal intensive care unit and hospitalized for (37.9± 16.4) days.Nine neonates suffered from respiratory distress syndrome but were eventually cured.Conclusions MCMA twin pregnancy has high morbidity and mortality.Early ultrasonography helps to clarify the diagnosis and enhance the monitoring,thus improving the perinatal outcomes.