Learn about the high risk fetal condition known as Twin-Twin Transfusion Syndrome in this clip from the series TWICE BORN. Twin-Twin Transfusion Syndrome is a condition in which identical twins share a placenta and pass the mother's blood unevenly between them, causing one twin to become too large and the other to become too small. The large baby has to pump too much blood for its heart to keep up with, while the small twin becomes too small to properly develop. As a result, both twins can die suddenly in utero. When diagnosed early, fetal surgeons may be able to intervene and correct the condition.