A hydatidiform mole results from over-production of the tissue that is supposed to develop into the placenta. The placenta normally nourishes a fetus during pregnancy. Instead, these tissues develop into a mass. The mass is usually made up of placental material that grows uncontrolled. Often, there is no fetus at all. The cause is not completely understood. Potential causes may include defects in the egg, abnormalities within the uterus, or nutritional deficiencies. Women under 20 or over 40 years of age have a higher risk. Other risk factors include diets low in protein, folic acid, and carotene. A hydatidiform mole is growth of an abnormal fertilized egg or an overgrowth of tissue from the placenta. Most often, a hydatidiform mole is an abnormal fertilized egg. The abnormal egg develops into a hydatidiform mole rather than a fetus (a condition called molar pregnancy). However, a hydatidiform mole can develop from cells that remain in the uterus after a miscarriage or a full-term preg