About 3% to 4% of all babies born in the United States have congenital abnormalities that will affect the way they look, develop, or function—in some cases for the rest of their lives.
Congenital abnormalities are caused by problems during the fetus's development before birth. It is important for moms and dads to be healthy and have good medical care before and during pregnancy to reduce the risk of preventable congenital anomalies.
Advances in perinatal testing and new diagnostic tests (i.e. amniocentesis, chorionic villus sampling, etc.) have made it possible to detect chromosomal and genetic related causes of congenital abnormalities earlier.
5 Categories of Congenital Abnormalities
Chromosome Abnormalities
Chromosomes are structures that carry genetic material inherited from one generation to the next. Twenty-three come from the father; twenty-three come from the mother. The genes carried on the chromosomes determine how the baby will grow, what she will look like, and to a certain extent, how she will function.
- When a child is born without 46 chromosomes, or when pieces of the chromosomes are missing or duplicated, she may look and behave differently from others her age and may develop serious health problems (e.g. Down syndrome).
Single-Gene Abnormalities
Sometimes the chromosomes are normal in number, but one or more of the genes on them are abnormal.
- Autosomal dominant inheritance is a genetic abnormality that can be passed on to the child if one of the parents has the same abnormality.
- Autosomal recessive inheritance is a genetic abnormality that can be passed on to the child only if both parents carry the same defective gene (e.g. Cystic fibrosis, Tay-Sachs disease, sickle cell anemia). In these cases, both parents are normal, but 1 in 4 of their children would be expected to be affected.
- X-linked conditions are genetic abnormalities that mainly occur in males (e.g. hemophilia, color blindness, forms of muscular dystrophy). Females may carry the abnormal gene that causes X-linked recessive disorders, but they may not show the actual disease.
- X-linked dominant conditions occur in both males and females; however, they are more severe in males (e.g. certain neurological conditions affecting the brain, skin disorders and types of skeletal or craniofacial disorders).
Conditions During Pregnancy That Affect The Baby
- Certain illnesses during pregnancy, particularly during the first nine weeks, can cause serious congenital abnormalities (e.g. maternal infections such as cytomegalovirus, chicken pox or rubella).
- Chronic maternal conditions (e.g. diabetes, hypertension, autoimmune diseases such as lupus, myasthenia gravis or graves disease) can negatively affect the developing fetus. Maternal hypertension can affect blood flow to the fetus impair fetal growth.
- Alcohol consumption and certain drugs during pregnancy significantly increase the risk that a baby will be born with abnormalities (e.g. fetal alcohol spectrum disorders).
- Eating raw or uncooked foods during pregnancy can also be dangerous to health of the mother and fetus and should be avoided.
- Certain medications, if taken during pregnancy, also can cause permanent damage to the fetus, as can certain chemicals that can pollute air, water, and food. Always check with your doctor before using any medication or supplement while you are pregnant.
Combination of Genetic and Environmental Problems
Some congenital abnormalities may occur if there is a genetic tendency for the condition combined with exposure to certain environmental influences within the womb during critical stages of the pregnancy (e.g. Spina bifida and cleft lip and palate).
Taking folate supplements prior to conception and during pregnancy decreases the risk of neural tube defects. However, there is also a genetic influence to this type of congenital anomaly.
Unknown Causes
The vast majority of congenital abnormalities have no known cause. This is particularly troubling for parents who plan to have more children, because there is no way to predict if the problem will reoccur.
If Your Family Has Experienced a Genetic-Related Birth Abnormality
Ask your pediatrician for a referral to a genetic counseling service. These services have expertise with a variety of genetic abnormalities and may be able to advise you as to the proper course of action.
Additional Information