Amniotic bands are thought to be caused by damage to a part of the placenta called the amnion. The placenta carries blood to a baby still growing in the womb. Damage to the placenta can prevent normal growth development.

Damage to the amnion may produce fiber-like bands that can trap parts of the developing baby. These bands reduce blood supply to the areas and cause them to develop abnormally.

The severity of the deformity can vary widely, from only 1 toe or finger being affected to an entire arm or leg missing or being severely underdeveloped. Symptoms may include:

• Abnormal gap in the face (if it goes across the face, it is called a cleft)
• All or part of an arm or leg missing (congenital amputation)
• Defect of the abdomen or chest wall (if band is located in those areas)
• Permanent band or indentation around an arm, leg, finger, or toe

The health care provider can diagnose this condition during a physical exam. This condition is usually diagnosed at birth.

Treatment varies widely. Often, the deformity is not severe and no treatment is needed. In more serious cases, major surgery may be needed to reconstruct all or part of an arm or leg.

Plans should be made for careful delivery and management of the problem after birth. The baby should be delivered in a medical center that has specialists experienced in caring for babies with this condition.

How well the infant does depends on the severity of the condition. Most cases are mild and the outlook for normal function is excellent. More severe cases have more guarded outcomes.

Complications can include complete or partial loss of function of an arm or a leg. Congenital bands affecting the hand often cause the most problems.