Definition of Amniotic constriction bands:

Amniotic constriction bands are strands of the fluid-filled sac (amniotic sac) that surrounds a baby in the womb. They may cause a congenital (present from birth) deformity of the face, arms, legs, fingers, or toes.

Causes, incidence, and risk factors:

Amniotic constriction bands are 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.

Amniotic constriction bands are rare.