molar pregnancy, a pregnancy in which a hydatid mole develops from the trophoblastic tissue of the early embryonic stage of development. The signs of pregnancy are all exaggerated: the uterus grows more rapidly than is normal, morning sickness is often severe and constant, blood pressure is likely to be elevated, and blood levels of chorionic gonadotropins are extremely high. The uterus must be evacuated because the mole may develop into a malignant trophoblastic disease, choriocarcinoma. See also hydatid mole.
