Back to guidelines homepage. This guideline provides clinicians with up-to-date evidence-based information regarding the management of monochorionic twin pregnancy. This is the second edition of this guideline, previously published under the same title in December A monochorionic pregnancy is a multiple pregnancy, most commonly a twin pregnancy, in which babies are dependent on a single, shared placenta. Monochorionic placentation can also occur in higher-order multiples. With the increasing use of assisted reproductive technology and sociodemographic changes in our population, there has been an increase in all types of multiple pregnancies. Monochorionic and dichorionic twin pregnancies share increased risks of preterm birth, fetal growth restriction, pre-eclampsia, maternal pregnancy symptoms and postpartum haemorrhage. The particular challenges of monochorionic pregnancies arise from the vascular placental anastomoses that are almost universal and connect the umbilical circulations of both twins. Specific complications associated with inter-twin vascular anastomoses include: twin—twin transfusion syndrome, selective growth restriction, twin anaemia-polycythaemia sequence, twin reversed arterial perfusion sequence and although not exclusive to monochorionic twin pregnancy, single intrauterine death is more common.
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