Birth defects

At one time while attending to a mother in labour, I was impressed by the progression of events. Fairly well growing spasms, no signs of emergencies, good dilation as the baby sinks into the cervix, enough energy to push and viola! We are done—only that there is no cry…. Why? Because what we have is one big mass with nothing else but a finger, which bounced three times and went still. Well being in my early years of practice, I had to leave the relaying of the disappointing news to the mother with the nurses as I went to recuperate.

What we delivered was the effect of congenital malformations, commonly known as birth defects. Congenital anomalies are physical abnormalities that occur before a baby is born. Birth defects happen to any part of any organ in the body. They are usually obvious at birth and manifest clearly by the time the child is one year old.

Some birth defects are more common than others. Birth defects are a leading cause of infant mortality. A birth defect is evident in about 7.5 percent of all children by the age of 5 years, although many of these are minor, Major defects are evident in about 3-4 percent of newborns. Several birth defects can occur together in the some infant.

Causes and risks
It is not surprising that birth defects are fairly common, considering the complexities involved in the development of a single fertilized egg into the millions of specialized cells that constitute a human being. Although the cause of most birth defects is unknown, certain genetic and environmental factors increase the chance of birth defects developing. These factors include exposure to radiation, certain drugs, alcohol and nutritional deficiencies, some infections in the mother, injuries and hereditary disorders. Some risks are avoidable. Others occur no matter how strictly a pregnant woman adheres to healthy living practices.

Exposure to harmful substances (teratogens)
A teratogen is any substance that can cause or increase the chance of a birth defect. Radiation (including x rays), certain drugs and toxins (including alcohol) are teratogens.

Most pregnant women who are exposed to tetarogens have newborns without abnormalities. Whether or not a birth defect occurs depends on when, how much and how long the pregnant woman was exposed to the teratogen.

Exposure to a teratogen most commonly affects the fetal organ that is developing at the time of exposure. For example, exposure to a teratogen during the time that certain parts of the brain are developing is more likely to cause a brain defect in those areas than exposure before or after this critical period. Many birth defects develop before a woman knows she is pregnant.

Nutrition
Keeping a fetus healthy requires maintaining a nutritious diet. For example, insufficient folic acid (folate) in the diet increases the chance that the fetus will develop spina bifida or other abnormalities of the brain or the spinal cord known as neural tube defects. Maternal obesity also increases the risk of neural tube defects.

Genetic and chromosomal factors
Chromosomes and genes may be abnormal. These abnormalities may be inherited from the parents, who can be affected by the condition or who can be carriers without symptoms. However, many birth defects are caused by seemingly random and unexplained changes (mutations) in the genes of the child. Most birth defects caused by genetic factors include more than just the obvious malformations of a single body part.

Infections
Certain infections in pregnant women can cause birth defects. Whether an infection causes a birth defect or not depends on the age of the fetus. The infections that most often cause birth defects are cytomegalovirus, herpesvirus, parvovirus, rubella. (German measles), varicella (Chicken pox), toxoplasmosis and syphilis. A women can have such an infection and not know it, because these infections can cause few or no symptoms in adults.

Diagnosis
During pregnancy, doctors assess whether a woman is at increased risk of having a baby with a birth defect. The chance is higher for women who are older than 35 years, have had frequent miscarriages or have other children with chromosomal abnormalities, birth defects or who have died for unknown reasons. These women may need special tests to find out if their baby is normal

A prenatal ultra sound can detect specific birth defects. Sometimes blood tests can also help. For example a high level of alpha fetal protein in the mothers blood may indicate a defect around the brain or spinal cord. Other invasive tests like amniocentesis or chorionic villi sampling are not common but can be used.

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