Birth defects are distincted as abnormalities of structure, function or body metabolism that are present at birth. These imperfections lead to mental or physical disabilities or are even fatal. There are more than 4,000 different known birth defects vary from minor to serious, and although many of them can be treated or cured, they are the leading cause of death in the first year of life. Birth defects can be caused by genetic, environmental or unknown factors.
In the United States, according to the March of Dimes, about 150,000 babies are born with birth defects each year. The American College of Obstetricians and Gynecologists (ACOG) says that out of every 100 babies born in the United States, three have some kind of major birth defect.
Structural or metabolic defects are those that emerge when a specific body part is absent or formed wrongly or when there is an inborn problem in the chemistry of body. In the United States the most common type of major structural defects is heart defects, which affect one in 100 babies. Some other common structural defects include spina bifida and hypospadias, a condition in which the orifice of the male urethra (where urine exits from the penis) is in the incorrect place. Metabolic defects affect one in 3,500 babies and typically include a missing or incorrectly formed enzyme (one of the proteins necessary for processing chemical substances in the body). This type of defect can be destructive or even fatal but doesn't usually cause any noticeable abnormalities in the child. Metabolic defects include Tay-Sachs disease - a fatal disease that affects the central nervous system, and phenylketonuria (PKU), which affects the way the body produces protein.
Defects caused by congenital infections hapen when a mother gets an infection before or during the pregnancy. The list of infections that can cause birth defects includes: rubella (German measles), cytomegalovirus (CMV), syphilis, toxoplasmosis, Venezuelan equine encephalitis, parvovirus and, rarely, chicken pox. Each of these infections doesn`t have an effect on 100% of babies whose mothers are infected during pregnancy. In case the mother is infected during early pregnancy, rubella bears the highest risk for birth defects - approximately 20%.
Other causes of birth defects include alcohol abuse by the mother and Rh disease, which can happen when "positive" or "negative" factors of mother's and baby's a blood type are different. Though some medications can cause problems, of the 200 most commonly prescribed drugs, none is connected with a significant risk of birth defects.
Multifactorial birth defects are caused by a combination of genetic and environmental factors and include neural tube defects and cleft lip and palate.
Look at the cause of birth-defects, types of faulty genes that call for birth defects.