Prenatal Screening and Diagnostic Tests & Procedures

What tests and procedures are necessary during pregnancy?

While you are pregnant your doctor or midwife may suggest a number of laboratory tests, ultrasound exams, or other screening tests. Read on to find out the basics of the most common tests done during pregnancy.

Screening Tests

Screening tests measure the risk of having a baby with some genetic birth defects. Birth defects are caused by problems with a baby’s genes, inherited factors passed down from the mother and the father. Birth defects can also occur randomly in people with no family history of that disorder. Women over the age of 35 have the greatest risk of having babies with birth defects.

The benefit of screening tests is that they do not pose any risk to the fetus or mother. But screening tests cannot tell for sure if the baby has a birth defect. So, they do not give a “yes” or “no” answer. Instead, screening tests give the odds of your baby having a birth defect based on your age. Women under the age of 35 will find out if their risk is as high as that of a 35 year old woman. For women over age 35, screening tests will help them find out if their risk for their age is higher or lower than average.

Some common screening tests used during pregnancy include:

Targeted Ultrasound
Maternal Serum MArker Screening Test
Nuchal Translucency Screening (NTS)

Diagnostic Tests

Diagnostic tests can give definite “yes” or “no” answers about whether your baby has a birth defect. But, unlike screening tests, they are invasive or come with a risk of miscarriage. Amniocentesis and chorionic villus sampling (CVS) are the two most commonly used. Both tests are more than 99% accurate for finding these problems. These tests also can tell you your baby’s sex. In most cases, results take about two weeks.

Common diagnostic tests include: