Birth Defects

Facing the harsh reality of a child with birth defects can be tough. No expectant parent imagines such a thing happening to her child. However, understanding why these things happen, learning methods of prevention and learning how to deal with what may come, is better than sticking ones head in the sand.

What are Birth Defects?


Birth defects are defined as an abnormality in the structure, function or metabolism of a newborn, which may lead to physical or mental disabilities, or eventually prove fatal. There are thousands of known birth defects. They are caused by genetic or environmental factors and while some can be diagnosed during pregnancy, others cannot.

Many birth defects can be treated, and new research has helped to find cures, some of which can be performed in the womb. Nevertheless, the loss of a baby during the first year of life is mostly attributed to these problems.

Birth Defect Types

Some kinds of defects seen in children are:

Structural and Metabolic Defects
When some internal or external part of the baby’s body is not formed properly, that is a structural defect. The most common structural defect is heart defects. Other types include, spina bifida, where the spinal cord is malformed, and malformations of the urinary tract and genital organs.

Metabolic defects cannot be seen externally. They are caused when certain enzymes in the body - needed to change one substance to the other, or to carry something from one place to the other - are not produced. Depending on what kind of enzyme the baby lacks, the affected areas may be the brain, eyes, blood or other organs.

Congenital Infection Defects
Pregnancy is a crucial time in the life of the mother and child. If the mother contracts an infection during this time, the baby can also become infected, which may result in birth defects. Some of the infections that can harm the baby include, toxoplasmosis, rubella, cytomegallo virus (CMV) or syphilis.

Other Defects
Other birth defects may be caused by alcohol or drug abuse during pregnancy, or the baby’s Rh factor differing from that of the mother.

Major Causes of Birth Defects

Birth defects are mainly caused by environmental factors, genetic disorders, or a combination of the two.

Genetic Disorders
Genetics play a significant role in the development of certain birth defects. Every living being has cells containing chromosomes, which contain the genes that dictate the unique characteristic of an organism. When a human embryo is fertilised, it gets half of its chromosomes from the father and the other half from the mother.

Birth defects may occur if the number of chromosomes passed on to the child is more or less than is required. Problems may also arise if any one of the chromosomes is faulty. Genetic birth defects in babies can occur even when both parents are healthy. Some of the inheritance patterns that may cause defects are:

  • Dominant Inheritance: Occurs when a child inherits a birth defect even though only one parent carries the defective gene. In these cases, the parent who passed the gene may be completely unaffected by it. This commonly occurs with achondroplasia, a kind of dwarfism.
  • Recessive Inheritance: When both parents carry the same recessive gene there is usually a one in four chance that they will produce a child who suffers from the recessive defect. Neither of the parents will display any signs that they carry this disease. Genes that are passed this way include cystic fibrosis and Tay Sachs disease.
  • Maternal Inheritance: Some defects are passed from mother to son, such as colour blindness and haemophilia.
  • Chromosomal Defects: If the number or structure of the chromosome passed on to the child is somehow different from the norm, defects such as Down’s syndrome may occur.

Environmental Factors
These include factors such as the mother’s exposure to radiation, chemical substances and drug or alcohol abuse.

Multifactor
Some birth defects may be a combination of genetic disease and environmental factors; for example, neural tube defects.

Common Birth Defects

Some of the commonly occurring birth defects in children are:

  • Heart Defects: In which the heart is not properly formed. This is one of the most common defects. The malformation may be a hole in the wall dividing the heart into its two chambers, or a contraction of the aorta, the most important blood vessel in the body.
  • Cerebral Palsy: Occurs when the baby’s muscles do not respond to commands. It may differ in severity depending on the individual. Some patients may have difficulty walking, others may not speak coherently.
  • Neural Tube Defects: During the first month of conception, the foetus’ brain and spinal cord begin to develop. If the tubal structure forming these organs is not completely formed, neural tube defects result occur. Two common tubal defects are: Spina bifida, which results when the column surrounding the spinal cord is not formed, and anencephaly, which occurs when the brain is not completely formed.
  • Congenital Hip Dislocation: The hipbone in some children may be improperly placed within the pelvic socket. If this defect goes untreated, the child may have difficult walking. This more commonly occurs in girls and is usually hereditary.
  • Congenital Hypothyroidism: The thyroid gland, located in the neck, is sometimes malformed, or completely undeveloped. This hampers growth and brain development. Oral thyroid hormone treatment can treat the defect, but only when this condition is caught early.
  • Clubfoot: All defects related to the leg (i.e. foot, ankle, joints, blood vessels or muscles) fall under this category. The leg may point upwards, or downwards and motion is limited. This defect is seen more in boys than girls and is treated by casting the leg just after birth.
  • Cleft Lip or Palate: Occurs when the lip of the baby is malformed or joined to the nose. This can be treated surgically.
  • Cystic Fibrosis: Affects the respiratory and digestive systems. In children with CF, the body is unable to move chloride, a chemical that the body requires to function properly, to different organs, resulting in respiratory and digestive problems. This disorder is genetic and parents with one child with CF can have genetic testing done to ensure that any subsequent babies are born healthy.
  • Gastrointestinal Defects: Internal structural defects that affect the stomach, intestines, oesophagus, diaphragm, rectum or anus of the child. The baby will have problems digesting, may vomit frequently or have difficulty swallowing. May be treated surgically at an early age to avoid further complications.
  • Down's Syndrome: A relatively common genetic defect caused by the presence of a 21st chromosome. Causes mental retardation, distinct physical characteristics and facial expressions, and heart problems. Depending on the severity of the child's Down Syndrome, the child may also behave violently under some circumstances.
  • Fragile X Syndrome: This genetic defect may be passed from one generation to the next before it manifests. A male with the abnormality passes the defect to his daughters. Any baby born to these carrier females has a 50% chance of exhibiting symptoms. The defect may cause learning disabilities, mental retardation, autistic behaviour and emotional problems.
  • Sickle Cell Anaemia: Passed from both parents, sickle cell causes severe anaemia, heart problems and severe pain, due to abnormal, sickle shaped red blood cells. Treatment for this defect may include blood transfusions, bone marrow replacement, cord blood transplants or antibiotics.
  • Tay Sachs Disease: Affects the central nervous system and may cause blindness, paralysis, deafness or dementia and is often fatal. Tay Sachs is a recessive gene that both parents must pass to the child. Persons of Ashkenazi Jewish and Eastern European descent commonly carry the gene.
  • Muscular Dystrophy: All genetic defects related to the muscles come under this category. Muscular dystrophy leads to weakness and degeneration of the muscles, including the heart.
  • Foetal Alcohol Syndrome: Caused by alcohol abuse during pregnancy. May lead to mental retardation, slow growth or abnormal facial features. There is no treatment, but foetal alcohol syndrome can be prevented by avoiding alcohol during pregnancy.
  • Most birth defects are abnormalities for which no one is to blame. The best way to deal with them is to be informed, practice preventative measures and seek a diagnosis early for the best treatment options.

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