The exact cause of<unk>  is unknown and can result from a number of causes. However, most cases show that the first three months in a pregnancy are when most birth defects occur because that is when the organs of the fetus are beginning to form. One common cause is amniotic band syndrome, which occurs when the inner fetal membrane (amnion) ruptures without injury to the outer membrane (chorion). Fibrous bands from the ruptured amnion float in the amniotic fluid and can get entangled with the fetus, thus reducing blood supply to the developing limbs to such an extent that the limbs can become strangulated; the tissues die and are absorbed into the amniotic fluid. A baby with<unk>  can be missing a portion of a limb or the entire limb, which results in the complete absence of a limb beyond a certain point where only a stump is left is known as transverse deficiency or amelia. When a specific part is missing, it is referred to as longitudinal deficiency. Finally, phocomelia occurs when only a mid-portion of a limb is missing; for example when the hands or feet are directly attached to the trunk of the body. Amnion ruptures can be caused by: * teratogenic drugs (e.g. thalidomide, which causes phocomelia), or environmental chemicals * ionizing radiation (atomic weapons, radioiodine, radiation therapy) * infections * metabolic imbalance * trauma<unk>  is the least common reason for<unk> , but it a study published in BMC Musculoskeletal Disorders found that 21.1 in 10,000 babies were born with a missing or deformed limb between 1981 and 2010 in the Netherlands, and the CDC estimates that 4 in 10,000 babies are born in the United States with upper limb reductions and 2 in 10,000 with lower limb reductions. During certain periods in history, an increase in<unk> s has been documented. One example includes the thalidomide tragedy that occurred in the 1960s when pregnant mothers were given a tranquilizer that contained the harmful drug, which produced an increase in children born without limbs.
Congenital amputation
Hand injury
Burn scar contracture
Brachial plexus injury
Heel stick wound
Malunion
Stingray injury
Vein graft failure