While any kind of birth defect is most heartbreaking to the parents of an infant, the ones which affect the limbs are especially problematic, since generally speaking an infant is otherwise perfectly healthy and will therefore have to deal with her or his disability when older.
Some birth defects affecting fetal limbs are easily corrected with the help of reconstructive surgery; yet many more will require years of therapy, adaptive technology, and help not only for the child who will need to learn to deal with the disabilities present, but also for the parents who need to be taught how to parent a child with a visible and irreversible birth defect.
Birth defects affecting fetal limb development may be broken down into several categories. By far the most common is congenital amputation which refers to the fact that due to unforeseeable problems in utero the blood supply to the affected limbs was restricted to such an extent that the forming limbs will cease any development. Infants present with entire limbs or parts of limbs missing. The precise grounds are unknown, although teratogens, radiation, and maternal antibodies are listed as possible causes.
Birth defects that present with a malformation of the fetal limbs are rarer but still do occur. It is interesting to note that several of these disorders, such as the split hand deformity which makes an infants hands appear to look like lobster claws because of missing middle digits, are actually mutations that can be traced back to chromosomal anomalies instead of external reasons, such as environmental pollutants, hazardous prescription drugs, or other factors acting on the mothers body and her unborn child.
Sometimes limbs affected by birth defects are a secondary anomaly that follows in the wake of a more serious fetal abnormality. For example, Downs syndrome is quite often associated with webbed toes, as is Timothy syndrome. The same is true for abnormally shortened digits and limbs, which are completely developed, yet evidence shortened bones, muscles, and ligaments. This is showcased during the presentation of Cushing syndrome quite frequently.
On the flipside of this birth defect is the formation of extra limbs or digits. While in some cases this points toward the death of a possibly conjoined twin early on in the pregnancy, there are also cases documented where the additional limb may be an inherited trait. This is quite frequently the case in families where the presentation of a superfluous toe may be traced through a number of generations of the family.
In some cases the birth defects affecting fetal limbs cannot be traced back to either chromosomal causation or external influences, and thus young families are quite frequently uncertain whether or not to pursue their dreams of having additional children for fear that the birth defect will show up again in another child. In other cases the disabilities forced upon the child are faced head on and couples are strengthened by their joint pursuit of helping the child cope with any disabilities she or he lives with.