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What is a birth defect?
A condition which is present from birth is called a birth defect. Some birth defects can be seen after the baby is born like clubfoot or extra fingers but some defects require tests even before the birth such as hereditary disorders tests, heart defects or hearing loss.
What causes birth defects?
Some birth defects are hereditary and some results due to chromosomes. Rarely some birth defects are caused by certain medications, infections and chemicals during pregnancy. Yet there are many defects with an unknown cause.
Most birth defects are multifactorial, which means that multiple factors are involved in their occurrence. The possible causative factors are as follows:
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Agent- A virus, interruption of blood supply, deficiency of nutrition like vitamin, maternal disease, environmental agent, chromosomal abnormalities The occurrence of the defects depends on the timing of the insult with respect to organogenesis and also the susceptibility of the embryo to these influences.
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Chromosomal defects occurring during the development of the gamete or the zygotes (the oocyte & the sperm).
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Genetic: Polygenic inheritance.
What factors increase the risk of having a baby with birth defects?
There are certain factors that can increase the risk of having a with a birth defect:
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Being old
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History of birth defects
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Have had a child with a birth defect
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Have diabetes or obesity
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Use certain medicines around the time you become pregnant
How to prevent birth defects?
Prevention of birth defects is not something we can achieve in absolute serious but can definitely aim at preventing or limiting it & keeping it to the bare minimum prevalence.
The general incidence of birth defects is about 2%, which includes the major birth defects that have a bearing on survival or quality of life of the offspring.
There are a few steps we can take to keep the prevalence of birth defects as low as possible. Screening plays an important part in the prevention of defects.
Pre-conceptional counselling is prudent in prevention. It should include a detailed evaluation of history, optimization of medical disorders, counselling about the use of recreational drugs etc.
A detailed history of genetic /chromosomal/congenital abnormalities should be elicited. The consanguinity of marriage also plays a role in genetic disorders which need evaluation.
Screening of couples prior to planning pregnancy for:
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Common genetic disorders
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General health- haemoglobin, weight, dietary habits, use of alcohol/smoking/recreational drugs
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Common diseases like diabetes, hypothyroid, and hypertension.
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The blood group of the parents
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Immunity status of rubella
a. Administer necessary treatment like:
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Treatment of Anemia
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Vaccination against rubella
b. Advised pre-pregnancy supplements
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Folic acid ( which should be started at least 3 months prior to)
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Vitamins
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Optimization of the medical diseases, treatment of the same.
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Evaluation of the medications- dose, teratogenic effects, if needed convert to safer drugs.
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Discontinue the teratogenic drugs
Consanguinity marriages among close relatives play an important role in increasing the risk of genetically induced anomalies many of which are serious & recurrent. Discouraging consanguinity is also important to prevent congenital anomalies.
Antenatal screening should be an integral part of antenatal care. It should be offered to all the women irrespective of the risk factors.
The screening methods are -
Ist Trimester- Double marker test, Nuchal Translucency scan for chromosomal abnormalities.
IInd trimester- Quadruple test, Anomaly scan for structural abnormalities
If any of these screening tests are abnormal, a diagnostic test becomes necessary which is called as a non-invasive prenatal test (NIPT) that screens for Down syndrome and other abnormalities in a baby. During pregnancy, some of the baby’s DNA passes into the mother’s bloodstream. The NIPT test analyses the genetic information contained in the DNA to screen for several abnormalities such as:
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Down syndrome
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Edwards syndrome
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Patau syndrome
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Turner syndrome
If an abnormality is detected then the pregnancy can be legally terminated till 20 weeks.
In spite of all the measures in place for prevention, it is very difficult to prevent or sometimes even predict the congenital abnormalities. Screening of the neonate is also an important aspect. So it is important to have a multi-disciplinary approach to deal with birth defects
