Birth Defects

Birth defects (or congenital disorders, as many people prefer to call them) come in many varieties. Some birth defects are serious, and result in lifelong difficulties for those who are born with them. Others are easily manageable, or even curable. Some birth defects are hereditary, running in families for generations, sometimes via recessive genes; others result from random genetic mutation. And sadly, some types of birth defect are caused by irresponsible behavior on the part of the mother.

Genetic Birth Defects vs Congenital Problems Caused by External Factors

Not all birth defects are caused by genetic abnormalities—some are caused by external factors such as maternal injury, maternal drug or alcohol abuse, etc.—and not all genetic abnormalities are heritable. While many of them (such as Leber’s hereditary optic neuropathy, for example) tend to run in families, many others (such as achondroplasia or fetal alcohol syndrome) are the result of random mutation or external factors.


Achondroplasia is a genetic condition associated with dwarfism (short stature, shortened limbs and digits, and enlarged head). This condition tends to be the result of genetic mutation (sometimes associated with advanced paternal age), although it can also occur when both parents carry the gene recessively.

Down’s Syndrome

Down’s Syndrome is caused by the failure of the 21st chromosome to separate while an egg or sperm cell is developing; that sperm or egg will therefore carry an extra copy of this chromosome, and the resulting embryo (and baby) will have 47 chromosomes, rather than the normal 46. The egg is the cause in 88 percent of cases. Adults with Down’s Syndrome typically have the mental ability of a seven- or eight-year-old child.

Amelia (Missing Limbs)

Children born with missing hands, arms, legs, or feet are said to suffer amelia. Amelia may be genetic in some cases, but the most common cause of this birth defect is interruption or prevention of limb formation between the 24th and 36th day of pregnancy (infection may be one reason this happens). There is also a very rare genetic disorder known as tetra-amelia syndrome,; children suffering from this condition are born without all four limbs. Tetra-amelia syndrome tends to be accompanied by a variety of other congenital medical problems—including malformations of the head, heart, skeleton, and lung—and babies born with this condition are often stillborn or die shortly after birth.


Congenital blindness can result from a number of causes, including:

  1. Bardet–Biedl syndrome (which is also associated with speech disorders)
  2. Congenital Rubella Syndrome, which may also cause deafness and intellectual disability, and can occur if the mother contracts rubella during the first trimester of her pregnancy
  3. Retinopathy of Prematurity (also known as Terry Syndrome), which is believed to be caused by the disorganized growth of the retinal blood vessels.
  4. Leber’s hereditary optic neuropathy, condition inherited from the mother, usually by male children, characterized by a degeneration of retinal ganglion cells, leading to a loss of central vision.


Congenital deafness can be caused by any of the following:

  1. Usher Syndrome: a genetic disorder also associated with vision loss
  2. Waardenburg syndrome: a genetic disease characterized by varying degrees of deafness
  3. Alport Syndome: another genetic disorder, which tends to cause hearing loss and kidney disease

Spinal Bifida

This condition is caused by an incomplete closing of the embryo’s neural tube—the precursor to the central nervous system of a fully developed child. Symptoms can include weakness and paralysis of the legs, abnormal movement of the eyes, pressure sores, and orthopedic conditions such as club foot. The likelihood of spinal bifida—which occurs in one out of every 1,000 live births—can be reduced up to 70 percent if the mother takes folic acid supplements on a daily basis prior to conception.

Fetal Alcohol Syndrome

Fetal Alcohol Syndrome (FAS) occurs when alcohol gets past the barrier created by the placenta and affects the developing fetus. Alcohol exposure in sufficient quantities — such as can occur with regular and/or heavy drinking — can stunt growth and cause serious harm to a developing baby’s brain and central nervous system. FAS is one of the leading causes of intellectual disability worldwide, and children born with this disorder also have a distinctive physical appearance. Perhaps the most tragic aspect of Fetal Alcohol Syndrome is its preventability—it differs from other types of birth defects in that all a pregnant woman needs to do to avoid inflicting this condition on her child is abstain from alcohol for nine months; this should be easy, especially compared to the myriad other lifestyle adjustments that must be made to accommodate pregnancy.

Congenital Hydrocephalus

Hydrocephalus is more commonly known as “water on the brain,” a slightly misleading description of a condition in which cerebrospinal fluid accumulates in various cavities in the brain. This creates pressure inside the skull and can cause tunnel vision and even enlargement of the head itself. The bones in the skull of a newborn have not yet bonded firmly, and this condition, if not treated properly, can result in permanent and severe physical deformity.

Cleft Lip

A cleft lip, also known as a harelip, occurs in one out of every 700 births, and results from abnormal development during pregnancy. A cleft lip appears as a gap in the child’s upper lip, which severely disfigures the face and can cause the infant to have difficulty feeding. A child with an uncorrected cleft lip may have speech difficulties, and many such children develop psychological problems stemming from the difficulty they face interacting with their peers. A cleft lip can be genetic, or it can be caused by maternal exposure to any number of environmental toxins.

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