Skip to navigation Skip to Content


Search Marshfield Clinic Health System
Join a world-class health system. Find jobs

Genetic Screening for Birth Defects

​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​​A birth defect is a mental or physical problem that is present at birth. A birth defect may affect how the body looks, works, or both. Many birth defects are mild, but some can be severe. Out of 100 newborns, only three to five have a major birth defect.

Although it is rare, some birth defects can cause the baby to die. Babies with birth defects may also need surgery or other medical treatments.

Some birth defects are inherited, meaning they are caused by a disease or condition that runs in the family. Other birth defects can be caused by exposure to harmful agents or other genetic causes. Sometimes the cause of a birth defect is unknown.

If you are concerned about your pregnancy, birth defects or other genetic conditions, you may wish to speak with a Genetic counselor.

Genetic counselors have specialized training in human genetics, and can provide you with information, counseling, and support.

There is no single prenatal test that can screen or diagnose all birth defects, but a detailed ultrasound can detect many problems and can often provide some peace of mind.

Age increases the risks

As couples age, there is an increased chance the baby could have some types of birth defects. The older the mother is at the baby’s due date, the greater the risk for chromosomal problems, such as Down syndrome.

As the father’s age increases over age 40, the risk for other genetic disorders increases.


Age of Mother at Due Date

Approx. Chance for Down Syndrome

Approx Chance for Chromosomal Problems


1 in 1500

1 in 525


1 in 1300

1 in 475


1 in 900

1 in 400 (.25%)


1 in 400

1 in 200 (.5%)


1 in 100

1 in 50 (2%)


1 in 30

1 in 20 (5%)