Single Fetal Demise at 10 - 14 Weeks of Monochorionic and Dichorionic Twin Pregnancy

BACKGROUND We examined the perinatal outcomes in cases of at least one fetal demise in monochorionic and diamniotic twin pregnancies. METHODS We reviewed the obstetric records of all Japanese twin pregnancies managed beyond 9 weeks' gestation at Japanese Red Cross Katsushika Maternity Hospital between 2008 and 2014. RESULTS The incidence in the monochorionic twin pregnancies was significantly higher than that in the dichorionic twin pregnancies (8.3% vs. 2.6%, odds ratio: 3.40, 95% confidence interval: 1.5 - 7.6, P < 0.01). Of these, 60.0% were diagnosed as fetal demise of both fetuses at the same time (vs. dichorionic twin pregnancy: odds ratio: 12.0, 95% confidence interval: 1.3 - 120, P = 0.04). The rate of "vanishing twin" in cases of at least one fetal demise at 10 - 14 weeks' gestation in the monochorionic twin pregnancies was significantly lower than that in the diamniotic twin pregnancies (30.0% vs. 88.9%, odds ratio: 0.05, 95% confidence interval: 0.01 - 0.53, P = 0.01). CONCLUSION The incidence of fetal demise and the influence on the co-twin in monochorionic twin pregnancy is greater than those in dichorionic twin pregnancy.