Congenital tends to mean present at birth, and the abnormality could be defined as something other than normal. Congenital anomalies are therefore those characteristics or differences that are present when a child is born, even if they are not immediately noticeable. There are many of these that can be caused by a variety of factors including genetics, unknown genetic change, or the environment. Sometimes the cause of birth defects, which many prefer to call anomalies, is simply not known.
One way to group congenital anomalies is by the body system they primarily affect, when and if they are present alone. For example, the most common of birth defects, heart defects, affects the cardiovascular system the most. These range from insignificant mild changes that are never noticed and can go away on their own, to severe and complex malformations of the heart that can alter its shape and function in profoundly dangerous ways.
Many congenital anomalies are related to growth of the bone or skeletal system. Some types that may fall within this range are any shape or clubfoot, fused fingers or hands, unusual growth or lack of growth of the skeletal structure, and congenitally shortened limbs, as might be present in children with Down syndrome. Cleft palate can also be in this group, although severe clefts can affect the sinuses and breathing as well.
There are congenital anomalies of the reproductive system and urinary tract. These include being born with both male and female reproductive elements or the lack of various elements that would allow reproduction. Fusion of the anus or ureter or communications between the rectum and vagina may be present in some children.
Many times when a child is born with birth defects, several systems are affected at the same time. It is not unthinkable for a baby to have defects in multiple areas, and these are often classified as a syndrome, although not always. For example, cerebral palsy, which is often thought of as being caused by a brain injury in the third trimester or at birth, can show a variety of weakness and poor function that will impair things like walking, most fine motor skills, and even talking and eating.
Certain syndromes are also marked by the ability to affect multiple areas. Down syndrome generally affects brain function and learning. Children are also characterized by epicanthic folds over the eyes, shorter limbs, and some difficulty with fine motor skills. They may also have heart defects or be prone to hypertrophic cardiomyopathy as adults.
Some children with heart defects have heterotaxy or Ivemark syndrome. In addition to complex heart defects, children may also have no spleen or many small, functional spleens. In contrast, conditions like spina bifida can cause problems with the lower half of the body and can affect walking and movement or things like bladder and bowel function.
Another thing that is true for some congenital abnormalities is that they may not be expressed at birth, and it may take months or even years before the abnormality is discovered. Certain organ defects may be minor at first, presenting little trouble for a newborn. Abnormalities may arise as the child grows, may worsen with age, or may cause aggressive deterioration of the entire body.
What can be said about congenital anomalies is that, fortunately, they are rare, but they have the capacity to impact almost any part of the body from the blood, the tissues, the skeletal system, and the major and minor organs. Although there are currently many ways to address some of these conditions, there are no ways to cure them all or minimize their impact on a child's life. It is not always possible to know who will have a child with a birth defect, although genetic testing can help if a family has a known genetic connection to certain diseases. It is also helpful to take folic acid supplements before conception and during pregnancy, as this has been shown to dramatically reduce the risk of certain birth defects.