The diets of vegetarians and vegans may not provide sufficient B12 unless a dietary supplement is taken. A deficiency may be characterized by limb neuropathy or a blood disorder called pernicious anemia, a type of anemia in which red blood cells become abnormally large. This can result in fatigue, decreased ability to think, lightheadedness, shortness of breath, frequent infections, poor appetite, numbness in the hands and feet, depression, memory loss, confusion, difficulty walking, blurred vision, irreversible nerve damage, and many others. If left untreated in infants, deficiency may lead to neurological damage and anemia. Folate levels in the individual may affect the course of pathological changes and symptomatology of vitamin B12 deficiency. Vitamin B12 deficiency in pregnant women is strongly associated with an increased risk of spontaneous abortion, congenital malformations such as neural tube defects, problems with brain development growth in the unborn child.