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Congenital abnormalities

congenital abnormalities
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 What are congenital abnormalities?

Congenital abnormalities are those which are caused during a baby’s development before birth. Improvements in medical care during pregnancy means that fewer babies are born with congenital problems, but when it does happen abnormalities can affect the way babies look, develop or function and these symptoms can be present for the rest of their lives. However, chromosomal and genetic abnormalities are increasingly detected early in pregnancy through technological advances such as amniocentesis, chorionic villus sampling and other diagnostic tests.

Healthychildren.org has this information about the different types of abnormalities, which have been grouped into five categories depending on the suspected cause.

Conditions During Pregnancy

Certain illnesses during pregnancy, and particularly through the very early stages, can cause serious congenital abnormalities. These include conditions such as German measles and diabetes, as well as external factors like alcohol consumption and certain drugs, which can significantly increase the risk that a baby will be born with anomalies.Particular medications taken during pregnancy can also cause permanent damage to a foetus so it’s important to check with your doctor before taking any medication whilst pregnant.

Chromosome Abnormalities

Chromosomes carry genetic material from one generation to the next and usually 23 chromosomes from both the mother and father form the building blocks of a new life. Genes carried on those chromosomes determine how the baby will grow, what they will look like and to some extent, how they will function.Where a child does not have the normal 46 chromosomes, or when pieces are missing or duplicated, they may look and behave differently to their peers. Down syndrome, for example, can occur when a child is born with just one extra chromosome.

congenital abnormalities

Genetic Abnormalities

Sometimes it is the genes which are passed on to a foetus that are abnormal, rather than the chromosomes themselves. A child can inherit these abnormalities if one of the parents is affected with the same abnormality – known as autosomal dominant inheritance. Some genetic problems are only passed to the child if both parents carry the same defective gene; such as cystic fibrosis, Tay-Sachs disease and sickle cell anaemia.In these instances, parents are not affected by the condition themselves, but can expect one in four of their children to be affected. This is known as autosomal recessive inheritance.

A third variety of genetic abnormality is ‘sex-linked’ and is generally only passed on to boys – although women may carry the abnormal gene that causes the disorder, again without showing signs of it themselves. Examples of this include haemophilia and common forms of muscular dystrophy.

Genetic and Environmental Problems

Some congenital abnormalities may occur when there is a genetic tendency for the condition as well as exposure to certain environmental influences within the womb during vital stages of pregnancy. Examples of this are spina bifida, cleft lip and cleft palate.

Unknown Causes

Despite the above known causes, the vast majority of congenital abnormalities have no known cause which can make it particularly troubling for parents who want to have more children. This is where genetic counselling may help.

 

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