An abnormal pregnancy with a cystic growth of the placenta hydatidiform mole develops from the trophoblastic tissue of the early embryonic stage of development. In a molar pregnancy, all of the usual signs are highly exaggerated. The growth of the uterus is unusually rapid, morning sickness is often severe and there are high levels of chorionic gonadotropin as well as high blood pressure. In such cases the uterus must be evacuated to prevent the mole from developing into choriocarcinoma. Also known as gestational trophoblastic disease or GTN.