First Trimester Screening and Testing

First trimester screening and testing is available to pregnant women as a way to determine if there will be a physical problem present at birth.

First trimester screening and testing includes:

• A blood test to measure pregnancy-associated plasma protein-A and human chorionic gonadotropin. The results of this blood test, along with the mother’s age, can help to determine the risk of carrying a baby with Down Syndrome or Edwards Syndrome.
• An ultrasound exam, specifically measuring the nuchal translucency.  This measures the size of clear space in the tissue at the baby’s neck.  An increase in this space may indicate Down Syndrome, trisomy 18 or other chromosome problems. When the thickness of this space is increased, it may also indicate a heart or other genetic condition.

What will the results tell me about my baby’s health?

Test results from first trimester screening and testing only indicate that there is an increased risk for your baby. Further testing will be needed to determine with certainty.

First trimester screening and testing confirms about 85 percent of women who are carrying a baby with Down Syndrome. Five percent of women have a false positive result, which means that the test result was positive but the baby doesn’t have an abnormality. Positive screening and test results mean that more testing is required to make a diagnosis. Those tests can include noninvasive prenatal testing, such as analyzing fetal DNA, chorionic villus sampling (CVS) that diagnoses chromosomal conditions, and amniocentesis that can diagnose chromosomal and neural tube defects. These tests are typically done in the second trimester.

Whatever your first trimester test results may be, your OB/GYN will help you to understand what they mean and guide you in the next steps.