Prenatal Testing Today

Women today have a myriad of choices when it comes to prenatal testing. While all of these tests have a similar goal—to detect chromosomal abnormalities and other possible birth defects in the fetus—they differ in many ways.

Timing: Some tests are done in the first trimester, some in the second and some over the course of the first and second trimester. It is an obvious advantage to have a safe, diagnostic test available as early as possible in pregnancy.

Screen vs. Diagnostic: A prenatal diagnostic test measures direct indicators (e.g., the exact number of chromosomes a fetus carries), while prenatal screening measures indirect indicators (e.g., alpha-fetoprotein (AFP) in maternal blood) to determine if there is a problem. In other words, a prenatal diagnostic test is a definitive means to determine if something is truly abnormal, whereas a prenatal screening test simply shows the likelihood of an abnormality existing.

Understanding the difference between a screening test and a diagnostic test is critical for women who are in the process of selecting from the ever-increasing prenatal testing options. The prenatal screening tests available today look primarily at certain protein levels in maternal blood, whereas the diagnostic tests are done directly on tissue or cells from the placenta or fetus.

Risk: While the diagnostic tests offered today more accurately and definitively determine the status of the fetus, they also carry a small but significant risk of causing miscarriage, infection or birth defects. For women of younger child-bearing age, an amniocentesis or CVS is typically recommended only after receiving an unfavorable result from one of the screening tests available.

At Artemis Health, our goal is to develop a prenatal test that is as safe as today’s screening tests and as accurate as today’s diagnostic tests by analyzing fetal cells or fetal DNA directly from maternal blood.