What are the Different Birth Defects Causes?

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  • Written By: Hillary Flynn
  • Edited By: Bronwyn Harris
  • Last Modified Date: 12 September 2018
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A birth defect is a physical or functional abnormality that develops due to factors occurring either prior to conception or during gestation. These abnormalities can cause mental or physical challenges and sometimes death. According to the United States Center for Disease Control and Prevention, an estimated three percent of infants in the United States are born with some type of birth defect. Though birth defects causes are often unknown, when they can be traced back to a source the cause is usually found to be either genetic or environmental. Genetic disorders are typically chromosomal abnormalities and environmental causes include teratogens such as drugs or alcohol, as well as infections.

When birth defects causes fall under the genetic disorders category, either one or both parents have probably passed a mutated gene to a fetus. Chromosomes in the cell nucleus contain genes which hold the blueprints for protein formation and determine inherited physical traits. Proteins are essential to building new cells that form the skin, muscles, bones, organs, and every other bit of human anatomy.

Sometimes when genetic material is translated from parent to fetus, a chromosome is lost or gained. Down's Syndrome is one of many examples of birth defects causes in this category, as it is the result of an extra chromosome. Other times, a chromosome gets rearranged or altered. This can result in myriad defects, including impaired cognitive functioning, cystic fibrosis, Tay-Sachs disease, and sickle cell anemia.


Environmental birth defects causes impact the fetus during development. Agents that can cause mutations in fetal development are called teratogens. Common teratogens are alcohol, drugs, and toxins. Fetal alcohol syndrome is one well known environmentally induced birth defect. Mothers who consume alcohol during pregnancy risk their baby being born with heart defects, developmental issues, learning disabilities, and structural problems with the face. Mothers who use illegal drugs also risk both physical abnormalities and mental disabilities. Some babies are born with drug addictions and go through withdrawal upon birth, which in itself can be harmful to the infant.

Another category of environmental birth defects causes is infection. Babies born to mothers who are infected with rubella, syphilis, toxoplasmosis, or cytomegalovirus during pregnancy have an increased risk of birth defects. However, it is impossible to precisely predict the affect of any teratogen because every case is unique. Each stage of the developmental process creates an environment that is more or less sensitive to certain factors, so the duration and timing of exposure has great impact.



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