One of the most common birth defects affecting children in North America is a cleft lip. The incomplete formation of the upper lip (cleft lip) or roof of the mouth (cleft palate) can occur individually or as a combined defect. The degree of severity varies may involve one or both sides of the face. A cleft or separation of the upper lip occurs very early in fetal development. During fetal development, certain components of the upper lip fail to form normally. A surgeon performs a cleft lip and/or cleft palate repair to correct this abnormal development and to restore function while giving the patient a more normal appearance. Most surgeons repair clefts with specialized plastic surgery techniques. The surgery improves the ability of the patient to eat, speak, hear, and breathe, in addition to restoring a more normal appearance.