Prenatal testing is offered in most pregnancies. Here's an overview of common prenatal screening tests:
|What it is||When it's done||What the results might tell you||Follow-up|
|Cell-free DNA (cfDNA) screening|
|Blood test||As early as week 10||Risk of Down syndrome (trisomy 21), trisomy 18, and fetal sex||Possible invasive testing, such as chorionic villus sampling or amniocentesis|
|First trimester screening|
|Blood test and ultrasound||11-14 weeks||Risk of Down syndrome (trisomy 21) and trisomy 18||Possible invasive testing, such as chorionic villus sampling or amniocentesis|
|Blood test||15-20 weeks||Risk of Down syndrome (trisomy 21), trisomy 18 and open neural tube defects, such as spina bifida||Possible targeted ultrasound, or invasive testing such as chorionic villus sampling or amniocentesis|
Some health care providers choose to combine the results of first trimester screening with the quad screen — although you won't learn the final results of this sequential testing until both tests are completed and analyzed.
In addition, fetal ultrasound often plays an important role in prenatal care and screening. Early in pregnancy, ultrasound can be used to confirm and date a pregnancy. Later, ultrasound can be used to detect certain birth defects and fetal anomalies, including neural tube defects.
Blood tests and ultrasounds pose limited risks for you and your baby. If the results of a blood test or ultrasound are positive or worrisome, your health care provider might recommend a more invasive diagnostic test — such as chorionic villus sampling or amniocentesis. These tests can be used to diagnose conditions, but they carry a slight risk of pregnancy loss.
If you're concerned about prenatal testing or wonder whether you need specific screening or diagnostic tests, discuss the risks and benefits with your health care provider.