The structural and functional abnormalities present at birth that lead to physical as well as mental disabilities are called birth defects. It is important to know what causes birth defects in order to take some preventive measures to reduce their occurrence. Read on the following article and learn more about common birth defects and their causes.
Birth defects are one of the serious concerns of scientists, doctors and parents around the world. There are different causes of birth defects of which more than half defects have unknown causes. Many of these birth defects or birth disorders are very severe in nature and turn out to be fatal conditions. There are a few conditions that are easily treatable, if detected soon after birth. It is important to know all about what causes birth defects. You can go through the following birth defects statistics and understand why awareness regarding causes of common birth defects is important.
Birth Defects: Statistics
- There are over 7.9 million infants around the world born with serious birth defects.
- Of these 7.9 million birth defects, more than 50% are idiopathic in nature. This means the causes of these birth defects are totally unknown.
- There are about 3.2 million children in the world who are disabled for life due to these birth defects.
- There is 1 in every 33 babies born with a birth defect.
- Most of the birth defects affect a developing fetus during the first 3 months of pregnancy.
- About 3% of the babies born in the United States suffer from a major birth defect at birth.
- The medical bills for children with birth defects is more than $1.4 billion per year.
Causes of Common Birth Defects
As you can see from the above statistics, birth defects is surely a very serious matter. Although not all birth defects can be prevented, but educating parents and creating awareness about what causes birth defects will help couples manage birth defects better. Let us have a look at the causes of birth defects that lead to structural and functional disabilities in children.
Genetic Factors Leading to Birth Defects
The genetic causes of birth defects are divided into three categories. These include: chromosomal abnormalities, single-gene defects and multifactorial influences. Let us learn more about each one in brief:
Chromosomes help determine the genetic makeup of an individual during conception. Any error during the coding of chromosomes can lead to birth defects. Usually there is an error that causes a baby to be born with extra or less number of chromosomes. In some cases, the chromosomes are rearranged or broken in structure causing a defect in the baby. Examples of chromosomal abnormalities include:
- Down syndrome (trisomy 21)
- Patau syndrome (trisomy 13)
- Edwards syndrome (trisomy 18)
- Turner syndrome (missing X chromosome in girls)
- Klinefelter syndrome (extra copy of X chromosome in boys)
Single Gene Defects
Birth defects caused by mutation of a single gene are placed in this category. Genes decide every single trait in an organism from the eye color to height to intelligence. These genes are passed on as 46 chromosomes placed in our cells. Half of the genes are inherited from each parent, that is, 23 from the mother and 23 from the father. This helps reduce the chances of passing on a faulty gene from a parent who may or may not have the disease. Thus, there is a 50% chance of inheriting a disorder from the parent. This type of inheritance is called dominant inheritance and examples of this kind of birth defects include:
- Marfan syndrome
- Phenylketonuria (PKU)
In many cases, birth defects occur when both parents carry a faulty gene and pass it on to their child. This type of inheritance is called a recessive inheritance and there are 25% chances of the child begin affected by the disorder. This occurs in cases of:
- Cystic fibrosis
- Tay-Sachs disease
- Sandhoff diseases
Many defects are found to be linked to the X chromosome. Thus, sons born of a mother carrying this defect have 50% chances of inheriting the disorder. Some of these birth defects include:
- Duchenne muscular dystrophy
Multifactorial Birth Defect
When a combination of genetic mutations along with presence of certain teratogens leads to abnormalities in the child, it is termed as a multifactorial birth defect. It so happens when a baby inherits certain genes, he/she is more likely to develop defects if exposed to certain environmental factors, like alcohol or cigarette smoke. Many times, deficiency of certain factors in the mother also leads to malformations in the fetus. Some examples of multifactorial birth defect include:
- Neural tube defects like anencephaly, spina bifida
- Cleft lip
- Heart defects
Environmental Factors Leading to Birth Defects
There are many environmental factors that are known as teratogens that cause birth disorders or birth defects in children. These teratogens in most cases can easily be prevented and save a child from developing these defects or abnormalities.
One of the most common causes of birth defects due to environmental factors is alcohol. There are about 1,000 to 6,000 babies born in the United States due to fetal alcohol syndrome (FAS). This condition causes mental as well as physical birth defects in babies. All because the mothers choose to drink alcohol during their pregnancy. It is, therefore, advised by doctors to pregnant women to abstain from drinking alcohol completely.
Smoking is very harmful to the growing fetus. Nicotine can pass through the placental barrier and cause many defects like slow growth, mental retardation as well as other neurological problems. It also increases chances of still births, low birth weight babies, cleft lip, etc.
Drug abuse is one of the leading cause of birth abnormalities. Use of illegal drugs like cocaine, marijuana, Ecstasy can cause harmful and irreversible effects of the growing fetus. Even use of medications without consulting the doctor can prove to be harmful. It is, therefore, advised to ask the doctor about each and every medications that you need to take during pregnancy. These medications although help relieving pain and other medical problems, can have adverse side effects on the baby. Thus, speak to the doctor before and after about the drugs that are termed to be safe for pregnancy.
Many infections affecting the mothers are also known to cause permanent disabilities in the children. For example, infection of cytomegalovirus (CMV) can lead to mental retardation, hearing loss and loss of vision in the baby. Sexually transmitted diseases like gonorrhea, syphilis, etc. can lead to bone defects and still births.
Exposure to certain chemicals like organic solvents, alcohols, paint thinners, varnish removers, nail polish removers, etc., increases the chances of birth defects in children. Women who work in beauty salons, dry cleaner shops, electronic chip manufacturing plants, etc. are more at risk of developing birth defects in their children.
Birth defects affect more than 150,000 children in the United States every year. Scientists have carried out years of research trying to find out the causes of these birth defects. Still there are more than half of the birth defects whose causes are still to be uncovered. It is always good to ask what causes birth defects, as awareness will help reduce their chances affecting babies who are yet to be conceived.