Classical symptoms and risks associated with an ongoing molar pregnancy in case of a coexisting twin

An uncommon presentation of molar pregnancy is a twin gestation with a normally developed fetus alongside a complete hydatidiform mole. Since the pregnancy of the normally developed fetus can progress to a viable term, continuation of a complete hydatidiform mole (CHM) can be allowed, whereby severe maternal molar-associated complications could develop. In this article we describe the pathophysiology and potential severe maternal mole-related morbidity associated with an ongoing molar pregnancy. Understanding the possibility of reaching a viable term of the healthy co-twin, and being aware of the risks of continuing a CHM pregnancy, is an essential part of informed and shared decision-making.