The First Trimester
Though most babies are born healthy, the risk of a child born with a birth defect concerns many parents.
Risks for certain types of birth defects, like open neural tube defects and down syndrome, can be assessed by screening tests during pregnancy. About 5 percent of those who have these screens are found to be at higher risk; in those cases further testing can be performed to achieve a definitive diagnosis.
Our Women's Care team provides top-notch care for both low-risk and high-risk pregnancies, so regardless of your results, you'll be in good hands!
First Trimester Screening Tests
First trimester screening is performed between 11 to 13 weeks of pregnancy, and involves both an ultrasound and a blood test.
Ultrasounds measure an area of fluid accumulation at the back of the baby’s neck called nuchal translucency (NT). This accumulation of fluid is a normal finding, but increased NT measurements may indicate a higher risk for chromosome abnormalities, congenital heart defects, and other genetic syndromes, and further testing is typically recommended.
- Blood test
A blood test (via a quick finger stick) measures the levels of two proteins, freeBeta-hCG and PAPP-A, which are normally found in the blood of pregnant women. The levels of these two chemicals are combined with the NT measurement and the mother’s age to provide a risk assessment for down syndrome and trisomy 18.
The combined testing detects about 85 percent instances of Down syndrome and 97 percent of trisomy 18. If your baby is determined to be at a higher risk for either of these conditions, you may want to have further diagnostic testing done, like chorionic villus sampling (CVS) or amniocentesis. If the test doesn't predict a higher risk, we typically recommend that you proceed with maternal serum AFP screening during your second trimester to identify risks for open neural tube defects and abdominal wall defects.
It's important to remember that a normal screening test doesn't guarantee a normal baby, nor do abnormal test results definitely mean a baby with a birth defect. Our doctors will talk with you about your results.