Perinatal outcome of monochorionic twin pregnancies

Objective To study the perinatal outcome of monochorionic (MC) twin pregnancies. Methods The 197 cases of MC twin pregnancies delivered in obstetric unit of Prince of Wales Hospital from Jan.2005 to Dec.2010 were enrolled in this retrospective study,which were divided into 3 groups:uncomplicated MC pregnancy (136 cases),twin to twin transfusion syndrome (TTTS,32 cases),selective intrauterine growth restriction (sIUGR,29 cases). Results (1) The gestational age at delivery in TTTS (30 weeks vs.37 weeks,P 25% in TTTS[5/15 vs.7.7% (10/130),P 25% was 17% (23/136) in uncomplicated MC pregnancy,52% (15/29) in sIUGR,63% (20/32) in TTTS.In uncomplicated MC pregnancy or sIUGR,pregnancies with EFW discordance>25% was associated with lower gestational age at delivery,higher incidence of preterm delivery and admission to NICU than those with EFW discordance≤25% (P 25% was associated with higher incidence of neonatal asphyxia (Apgar score 1 minute≤7) than those with EFW discordance≤25% (P<0.05). (7) Compared to uncomplicated MC pregnancy,the incidence of umbilical artery (Um A) flow abnormality was higher in TTTS[38% (12/32) vs.9.6% (13/136),P<0.01]or sIUGR[41% (12/29) vs.9.6% (13/136),P<0.01].The incidence of IUFD in pregnacies with Um A flow abnormality was 2/13,6/12 and 5/12 respectively in uncomplicated MC pregnancy,TTTS and sIUGR. Conclusions MC pregnancies complicated by either TTTS or sIUGR have poorer perinatal outcome as compared with uncomplicated MC pregnancies.MC pregnancies with EFW discordance>25% and Um A flow abnormality are associated with even worse perinatal outcome.Close fetal monitoring is needed in MC pregnancies in order to reduce perinatal mortality. Key words: Twins,monochorionic; Fetofetal transfusion; Fetal growth retardation; Birth weight; Pregnancy outcome