What is a birth defect? What are the various causes of a birth defect? #birthdefect #congenitalanomaly

What is a birth defect?

Most of you would have come across a baby with a birth defect. This is a condition where the baby is born with one or more defects in his or her formation. These could be obvious structural problems or could be less obvious but complex genetic problems (usually leading to multiple defects).

What causes a birth defect?

As we can imagine, there is nothing more complex than the huge changes that take place, when the baby develops from a single cell (formed by the fusion of the egg and sperm to form the zygote), to a complex fully developed baby (organism).

So, you might be wondering what causes a birth defect. We have different causes and you have broad groups:

Malformation: This is a situation where the formation is not complete or it’s not proceeding as it should. This is like a glitch or error in a computer file, for example. So, genetic information could be abnormal. There could be changes in the genetic information called mutations which dictate the tissue formation in a different way. There could be some other factors like a nutritional deficiency or drug exposure which affect the fetus formation in the embryonic stage. Cleft lip or palate, heart defects, extra fingers or toes, fused digits are examples.

Disruption-The next important factor is what we call disruption-when the organ is starting to be form normally, but some factor actually disrupts it. One good example is the amniotic band related disruption. The amnion is one of the membrane layers covering the developing fetus within the womb (amniotic cavity, containing the amniotic fluid in which the fetus floats). This membrane which covers the baby (part of it) becomes loose. This loose membrane floats in the amniotic fluid, and it might wrap around a portion of the baby like a limb or digit, which it disrupts. We often see quite serious problems, including a fully amputated limb in this condition. A real shame, as the pregnancy would otherwise be perfectly normal.

Deformation: Deformation occurs when something is formed but it is bent or deformed by space constraints-this could happen in multiple pregnancies, this could happen in a very small uterine sac in a mother who is young and the uterus is tight, or it could be a uterine myoma (tumor in the uterus) or some other space-occupying lesion. One example of the deformation sequence is Potter’s syndrome.

Potters sequence or Potter’s syndrome happens when the fetus has a major kidney (renal) abnormality that affects both kidneys. This results in very reduced urine output. Since the amniotic fluid is significantly dependent on the fetal urine output, there is reduced amniotic fluid (severe oligohydramnios). When the fluid surrounding the baby is low, this leads to a problem in lung development-there needs to be fluid in the womb for the baby to breathe and the lung to develop. This leads to pulmonary hypoplasia-the baby may also have problems with physical features-limbs are cramped and deformed and you may have facial features which are abnormal as well.

What next?

The news of any abnormality in their newborn baby comes as a huge shock to the parents. We need to support them. Depending on what the problem is, and whether there are associated problems, the doctor (medical team) will decide on the next steps and advice the family accordingly. It might be necessary to carry out more tests (like ultrasound scans, MRI and genetic tests) and other experts might need to be involved as well.

I have taken the images from different sources online, I would like to thank the sources.

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