Decision Guide: Which prenatal tests are for you?
Your healthcare provider will offer you a range of genetic screening and diagnostic tests during your pregnancy. Some are simple blood tests, while others involve more invasive procedures — and all are optional. Before you agree to any test, ask your caregiver to explain what it is, how it’s done, whether the test itself is risky in any way, and what the results will tell you. Many prenatal tests are for screening rather than diagnostic purposes. Screening tests give you a sense of your risk for certain conditions. But only a diagnostic test can tell you for sure whether your baby has a problem. Here are your options during the first trimester:
Inside pregnancy: How food reaches your baby
A 3D animated look at how the food you eat gets broken down into tiny elements, is absorbed into your bloodstream, then passes through the placenta to your baby.
First-trimester combined screening test: This relatively new screening test combines a nuchal fold scan (using ultrasound to measure the clear space in the tissue at the back of your developing baby’s neck) with a blood test to measure two proteins. The scan is performed between 11 weeks of pregnancy through the end of 13 weeks, and the blood test may be done at the same time or possibly a few weeks earlier. First-trimester combined screening gives you information about your baby’s odds of having Down syndrome and may tell you whether your baby’s at higher risk for a few other problems as well. Although it’s not diagnostic, the screening is essentially risk-free and may help you decide whether you want invasive diagnostic testing such as chorionic villus sampling (CVS) or amniocentesis, which slightly increase the risk of miscarriage.
Chorionic villus sampling (CVS): This diagnostic test involves collecting cells from the placenta, which are then sent to a lab for genetic analysis. CVS can identify whether your baby has any of hundreds of chromosomal abnormalities and other genetic disorders. It’s done in the first trimester, usually between 11 and 12 weeks, making it an earlier alternative to another diagnostic genetic test called amniocentesis, which is done between 16 and 20 weeks.