The first few weeks of fetal development are fraught with peril for the developing embryo. Any disruption or error in fetal development during the weeks when organs and major body systems are forming can result in congenital defects. Maternal illness, alcohol or drug use, or chemical exposure can cause birth defects. In many cases, the reason is never known. Some malformations are more common than others.
Cleft Lip Deformity
Cleft lip deformity is the single most common birth defect in the United States, occurring in 1 in 700 births, the Pediatric Plastic Surgery and Craniofacial Associates says. Cleft lip deformities are incomplete closures or tissue malformation in the area between the lip and nose, and may involve one or both sides of the lip. The palate, the roof of the mouth may also be malformed. Cleft palate can be surgically repaired. Usually more than one surgery is required, and speech therapy may also be necessary.
Cardiac Defects
Cardiac defects are the most common group of congenital defects, occurring in 1 percent of births, the American Heart Association says. There are many types of cardiac defects. Some are defects of the bloods vessels leading into and out of the heart; others are caused by problems with the structure of the heart itself. Hypoplastic left heart, where the left side of the heart and bloods don't develop properly, is an example of a common cardiac abnormality. Atrial septal defect, or ASD, which is a hole between the left and right atrium, is another. Aortic stenosis and coarctation of the aorta are defects caused by a narrowing of part of the aorta.
Clubfoot
Clubfoot, formally known as talipes equinovarus, occurs in 1 in 1,000 births, the March of Dimes reports. Boys are born with the disorder twice as often as girls. In 50 percent of cases, both feet are affected. The cause of clubfoot is abnormalities in the bones, muscles and ligaments of the foot, which points downward and inward and makes it very difficult to walk. Because a baby's bones are still bendable, manipulation and casting usually treat the condition successfully. Some cases can be resolved in just a few months with casting of the foot.
Neural Tube Defects
Neural tube defects occur once in every 2,000 births. Two common forms of neural tube defects are spina bifida, in which the spinal cord isn't completely enclosed, and anencephaly, in which part of the brain is absent. Neural rube defect occurs early in pregnancy when the structure that forms the brain and spinal cord doesn't fold into a tube around Day 29, says KidsHealth. Folic acid supplements decrease the chance of having a baby with neural tube defects. Spina bifida may be mild or severe. Some children with spina bifida can walk; others are paralyzed. Anencephalic infants rarely survive more than a few days.
