Birth defects are physical problems which exist at birth. Birth defects can affect the body’s visual appearance, how it functions or both. Numerous birth defects are minor, however some may be significant. Babies who have birth defects may require surgical procedures or medical treatments. Screening tests can provide information regarding an expectant woman’s risk for delivering a baby with specific birth defects. Not every birth defect can be detected by screening tests prior to birth.

Some of the birth defects that screening tests are available for include:

• Abdominal wall defects - A particular form of defect that takes place when the muscle and skin which cover the abdomen wall are absent and the bowel protrudes through an opening in the abdominal wall (gastroschisis). An additional kind is when the tissue surrounding the umbilical cord is fragile and permits organs to stick out into this area (omphalocele).
• A Neural tube defect - Partial closure of the fetal spine which could cause spina bifida or anencephaly.
• Down syndrome - Mental retardation, irregular facial features, and medical difficulties like heart defects happen because of an extra chromosome 21 (named Trisomy 21).
• Heart defect - The chambers or pathways through the heart are not properly developed.
• Trisomy 18 - Existence of an extra chromosome 18, that results in severe mental retardation, other birth defects and sometimes even death.

All pregnant women are offered screening tests to evaluate their chances of delivering a baby that has a birth defect or a genetic disorder. If the screening test indicates an elevated risk for a baby with defects, additional tests could possibly be performed to identify the problem. An irregular screening test outcome, although worrisome, merely indicates a potential issue. In most instances, the baby has good health despite the abnormal screening test results. Similarly, a birth defect may appear despite the test results not showing any problems.

The screening tests in the first trimester consist of an ultrasound exam and blood tests. These screening tests can be performed together as a combined test or in a step-by-step method. Some women might not require additional testing. These first trimester screenings are carried out between the 11 to 14 week range of pregnancy to determine the risk for Down syndrome and Trisomy 18.

Blood tests will measure the amount of two materials in the mother’s blood:

1. Pregnancy-Associated Plasma Protein-A ( known as PAPP-A)

2. Human Chorionic Gonadotropin (HCG)

An ultrasound examination called nuchal translucency screening, is utilized to evaluate the thickness at the back of the neck of the fetus. An expansion in this area could be a indication of Trisomy 18, Down syndrome, as well as other chromosomal problems.