How to Detect Down Syndrome While Pregnant


Down syndrome is a genetic disorder that happens when your baby has an extra chromosome, usually a copy of chromosomes 18 or 21. That extra chromosome leads to developmental delays and characteristic facial features associated with Down’s. There’s no way to prevent Down syndrome, but genetic counselors may be able to help you predict how likely you are to have a Down syndrome baby. Screening tests during pregnancy can help you find out if your baby has this condition.

Step 1

Schedule an appointment with your doctor as soon as you find out you’re pregnant for a first-trimester ultrasound. This is done to look for and measure growth patterns in your developing fetus and to look for extra fluid associated with chromosomal abnormalities. Have your blood tested for pregnancy-associated plasma protein-A (PAPP-A) and human chorionic gonadotropin, or HCG. If these tests indicate an abnormality, it doesn’t mean your baby will definitely have Down syndrome. Your doctor will need to perform more tests.

Step 2

Schedule an appointment at 15 to 20 weeks for what’s commonly called the “quad screen” test. The quad screen checks your levels of alpha-fetoprotein, HCG, inhibin A and estriol. Your doctor will determine if your test results indicate an increased risk of Down syndrome and then order more tests. As many as 1 in 20 women will have a test result that indicates an increased risk of Down syndrome in one or more of these tests, then deliver a healthy baby who doesn’t have Down’s, according to

Step 3

Schedule amniocentesis after 14 weeks or chorionic villus sampling, or CVS, after 15 weeks to confirm with 98 to 99 percent certainty that your baby does or does not have Down syndrome. CVS carries a 1-in-100 risk of causing miscarriage and amniocentesis carries a 1-in-200 risk. Weigh the benefits of these tests with their risks.



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