Screening Tests for Birth Defects

Can Birth Defects Be Avoided?

There are some screening tests that can be done to assess a pregnant woman’s risk of having a baby with certain defects. These tests may also help the doctor get an idea of any problems you may have during the pregnancy.

Of 100 newborns only about two or three have major birth defects. There are defects that can be avoided, such as avoiding smoking or drinking, but others are a result of a congenital disorder or malformation. There is still a lot of research being done in this area and unfortunately for a little more than half of the newborns born with a defect the cause isn’t known.

What are Birth Defects?

A birth defect may affect how the body looks, works, or both. Many birth defects are mild, but some can be severe. Babies with birth defects may need surgery or medical treatment. Most birth defects occur during the first 3 months of pregnancy and others appear at birth or later in life. Some of the most common birth defects found through screening tests include:

Neural tube defect: Incomplete closure of the fetal spine that can result in spina bifida or anencephaly. Abdominal wall defects: One type of defect occurs when the muscle and skin that cover the wall of the abdomen are missing and the bowel sticks out through a hole in the abdominal wall (gastroschisis). Another type is when the tissue around the umbilical cord is weak and allows organs to protrude into this area (omphalocele). Heart defect: The chambers or pathways through the heart are not properly developed. Down syndrome: Mental retardation, abnormal features of the face, and medical problems such as heart defects occur as a result of an extra chromosome 21 (trisomy 21). Trisomy 18: There is an extra chromosome 18, which causes severe mental retardation and birth defects and sometimes death.
Most screening tests are offered to all pregnant women to assess their risk of having a baby with a birth defect or genetic disorder. If a screening test shows an increased risk of having an affected baby, further tests may be used to diagnose the problem. An abnormal screening test result, while alarming, only signals a possible problem. In most cases, the baby is healthy even if there is an abnormal screening test result.

What Tests are Available for Birth Defects?

Women at increased risk of having a baby with a birth defect may be offered a diagnostic test first rather than having a screening test. These risk factors may include:

· Family or personal history of birth defects
· Previous child with a birth defect or genetic condition
· Use of certain medicines around the time of conception
· Diabetes before getting pregnant

Talk with your gynecologist about whether or not you need to have further tests. These screening tests can help assess the risk of a birth defect. Some tests are offered to all pregnant women. Other tests may be offered based on your history or risk factors. You gynecologist will also be able to explain in detail about tests and answer any questions you may have.